Abstract
The effect of blue LED on melatonin secretion, feeding behaviour and growth was addressed in Holstein female dairy calves. In Exp.1, six animals (8 weeks old, 97 ± 4.1 kg BW) were exposed to yellow or blue LED for 2 hr before darkness over 7 days under a long-day photoperiod (LDPP). In Exp. 2, six animals (8 weeks old, 88.5 ± 4.8 kg BW) were exposed to blue light from a white LED all daytime or a yellow LED for 2 hr before the darkness of LDPP (blue light cut) over 3 weeks. In Exp. 1, blue light mildly suppressed melatonin secretion during the 2-hr treatment but did not affect the timing of the nightly melatonin rise. However, the rise in nighty melatonin levels was higher with yellow than blue LED. In Exp. 2, white LED completely suppressed melatonin secretion during the 2-hr treatment, but plasma melatonin concentrations were similar during the darkness. Grass hay intake, rumination time, frequency of water intake and body weight gain were higher in animals exposed to the yellow rather than the white LED. Overall results indicate that exposure to blue light from white LEDs under an LDPP suppresses melatonin secretion and might negatively impact the development of female dairy calves.
https://pubmed.ncbi.nlm.nih.gov/32219969/
Melatonin og lys
Melatonin er et signalstof, som findes i alle levende væsener: mennesker, dyr og planter. Melatonin kaldes for kroppens naturlige sovemiddel. Det skyldes, at stoffet stimulerer søvnen og søvnkvaliteten. Melatonin er samtidig en kraftig antioxidant, som styrker immunforsvaret og er med til at beskytte kroppens celler og væv. Desuden modvirker melatonin hurtig ældning, stress og kolesterol.
Beskrivelse
Hvor og hvordan produceres melatonin?
Hos mennesker produceres melatonin i koglekirtlen i hjernen, baseret på signalstoffet serotonin. Serotonin bidrager til reguleringen af søvn, humør, appetit og hukommelse.
Kroppens indhold af serotonin stiger ved skumringstid, og den begyndende udskillelse af melatonin sætter søvnrytmen i gang. Har du for lidt serotonin i kroppen om aftenen, påvirker det produktionen af melatonin og dermed søvnkvaliteten.
Det er vigtigt for produktionen af melatonin, at der er nok serotonin tilgængeligt i kroppen. Dette kan sikres ved at indtage vitamin B6 og fødevarer, der indeholder tryptofan, som er forløberen for serotonin. Disse fødevarer kan fx være; hytteost, brune ris, avocado, bananer, valnødder, tomater, sojaproteiner og kalkun.
Derudover afhænger mængden af melatonin i høj grad af lysstyrken i omgivelserne. Jo mørkere omgivelserne er, jo mere melatonin produceres.
Lysstyrken (dag/nat) opfanges af fotoreceptorer i øjets nethinde, som sender en besked til kroppens indre ur – en lille gruppe nerveceller i hjernen. Det indre ur registrerer lysstyrken over tid og kan dermed styre f.eks. døgnrytmen, og produktionen af melatonin i koglekirtlen.
Produktionen af melatonin er på sit højeste hos 5-10 årige og falder derefter med alderen.
Hvornår produceres melatonin?
Produktionen af melatonin fremmes i mørke og hæmmes i lys. Det er derfor, dette signalstof også kaldes mørkets hormon, hvilket det ikke er.
En naturlig produktion af melatonin foregår derfor om aftenen og især om natten, hvor øjnene er naturligt omgivet af mørke – og dermed ikke udsættes for hverken dagslys eller kunstig belysning.
Brugen af kunstig belysning om aftenen og om natten reducerer varigheden af melatoninproduktionen. Dette medfører uorden i mange af kroppens funktioner og anses af forskere for at være årsagen til den stigende forekomst af søvnproblemer, men også brystkræft og andre former for kræft i de industrialiserede lande.
Hvilket lys påvirker produktionen af melatonin?
I vores moderne verden er vi udsat for lysforurening om aftenen og natten, som kommer fra indendørs og udendørs belysning, computere, TV, tablets og smartphones. Denne lysforurening er kendetegnet ved at afgive blåt lys og skaber en ubalance i vores naturlige døgnrytme ved at hæmme den naturlige produktion af melatonin. Det er det blå lys i lysspektret (446-477 nanometer), der hæmmer produktionen af melatonin.
Hvor længe producerer kroppen melatonin?
Over en 24-timers periode kan kroppen højst opretholde en maksimal produktion af melatonin i 12 sammenhængende timer. Normalt varer den daglige maksimale produktion af melatonin hos voksne 9-10 timer i træk.
Der vil dog altid være en ubetydelig minimal produktion af melatonin, uanset lysforhold.
Melatonin og søvn
Behovet for søvn kan variere meget fra person til person og afhænger blandt andet af melatoninproduktionen. Børn og unge har brug for mange timers søvn pr. dag (10-15 timer), mens voksne og ældre kan klare sig med langt færre timers søvn pr. dag (5-10 timer).
Det er derfor vigtigt at sikre, at øjnene ikke udsættes for blåt lys i de anbefalede 8-10 timer pr. dag, hvor kroppen producerer det melatonin, der er nødvendigt for at sikre en god søvn foruden sygdomsbekæmpende kropsfunktioner.
Hvis du ikke har mulighed for at sove 8-10 timer i døgnet, findes der simple og bivirkningsfrie metoder, såsom søvnbriller, til at sikre melatoninproduktionen – uden at ændre livsstil.
Melatoning og søvnbriller
Den naturlige løsning til at sikre produktionen af melatonin er søvnbriller, som blokerer blåt lys op til 530 nanometer i lysspektret.
Du kan nemt se TV, arbejde med computeren og læse med søvnbriller på. Du kan opretholde stort set alle dine normale aktiviteter efter mørkets frembrud – og samtidig sikre en sund og naturlig produktion af melatonin.
Det er også muligt at bruge specielle lyskilder, der filtrerer det blå lys fra og opnå samme effekt.
Forskning vedrørende melatonin og lys
Eksponering for blåt LED-lys før mørkets frembrud under en lang dag med lys ændrer melatoninsekretion, fodringsadfærd og vækst hos hunmalkekalve
Anim Sci J. 2020 Jan-Dec;91(1):e13353. doi: 10.1111/asj.13353.Mabrouk Elsabagh, Mamiko Mon, Yui Takao, Akiko Shinoda, Takashi Watanabe, Shiro Kushibiki, Taketo Obitsu, Toshihisa SuginoPMID: 32219969 / DOI: 10.1111/asj.13353
Effekten af blå LED på udskillelse af melatonin, fodringsadfærd og vækst blev undersøgt hos holsteinske hunmalkekalve. Overordnede resultater indikerer, at eksponering for blåt lys fra hvide lysdioder i løbet af...
Eksponering for blåt LED-lys før mørkets frembrud under en lang dag med lys ændrer melatoninsekretion, fodringsadfærd og vækst hos hunmalkekalve
Effekten af blå LED på udskillelse af melatonin, fodringsadfærd og vækst blev undersøgt hos holsteinske hunmalkekalve. Overordnede resultater indikerer, at eksponering for blåt lys fra hvide lysdioder i løbet af en hel dag med belysning, undertrykker udskillelsen af melatonin og kan have en negativ indvirkning på udviklingen af kvindelige malkekalve.
Exposure to blue LED light before the onset of darkness under a long-day photoperiod alters melatonin secretion, feeding behaviour and growth in female dairy calves
Anim Sci J. 2020 Jan-Dec;91(1):e13353. doi: 10.1111/asj.13353.
PMID: 32219969 / DOI: 10.1111/asj.13353
Systematisk gennemgang af lyseksponerings indvirkning på den menneskelige døgnrytme
Chronobiol Int. 2019 Feb;36(2):151-170. doi: 10.1080/07420528.2018.1527773. Epub 2018 Oct 12.Leena Tähkämö, Timo Partonen, Anu-Katriina PesonenPMID: 30311830 / DOI: 10.1080/07420528.2018.1527773
En række undersøgelser tyder på, at mistimet lyseksponering forstyrrer døgnrytmen hos mennesker, hvilket potentielt kan forårsage yderligere helbredspåvirkninger. Yderligere analyse af disse 15 rapporter viste, at to timers eksponering for...
Systematisk gennemgang af lyseksponerings indvirkning på den menneskelige døgnrytme
En række undersøgelser tyder på, at mistimet lyseksponering forstyrrer døgnrytmen hos mennesker, hvilket potentielt kan forårsage yderligere helbredspåvirkninger. Yderligere analyse af disse 15 rapporter viste, at to timers eksponering for blåt lys (460 nm) om aftenen undertrykker melatonin, idet den maksimale melatonin-undertrykkende effekt opnås ved de korteste bølgelængder (424 nm, violet). Udsættelse for lys om aftenen, om natten og om morgenen påvirkede døgnrytmen og melatoninniveauet. Derudover frembragte selv de længste bølgelængder (631 nm, rød) og lave lysniveauer (5-10 lux) en døgnrytmerespons,, når man sov med lukkede øjne.
Systematic review of light exposure impact on human circadian rhythm
Chronobiol Int. 2019 Feb;36(2):151-170. doi: 10.1080/07420528.2018.1527773. Epub 2018 Oct 12.
PMID: 30311830 / DOI: 10.1080/07420528.2018.1527773
Abstract
Light is necessary for life, and artificial light improves visual performance and safety, but there is an increasing concern of the potential health and environmental impacts of light. Findings from a number of studies suggest that mistimed light exposure disrupts the circadian rhythm in humans, potentially causing further health impacts. However, a variety of methods has been applied in individual experimental studies of light-induced circadian impacts, including definition of light exposure and outcomes. Thus, a systematic review is needed to synthesize the results. In addition, a review of the scientific evidence on the impacts of light on circadian rhythm is needed for developing an evaluation method of light pollution, i.e., the negative impacts of artificial light, in life cycle assessment (LCA). The current LCA practice does not have a method to evaluate the light pollution, neither in terms of human health nor the ecological impacts. The systematic literature survey was conducted by searching for two concepts: light and circadian rhythm. The circadian rhythm was searched with additional terms of melatonin and rapid-eye-movement (REM) sleep. The literature search resulted to 128 articles which were subjected to a data collection and analysis. Melatonin secretion was studied in 122 articles and REM sleep in 13 articles. The reports on melatonin secretion were divided into studies with specific light exposure (101 reports), usually in a controlled laboratory environment, and studies of prevailing light conditions typical at home or work environments (21 studies). Studies were generally conducted on adults in their twenties or thirties, but only very few studies experimented on children and elderly adults. Surprisingly many studies were conducted with a small sample size: 39 out of 128 studies were conducted with 10 or less subjects. The quality criteria of studies for more profound synthesis were a minimum sample size of 20 subjects and providing details of the light exposure (spectrum or wavelength; illuminance, irradiance or photon density). This resulted to 13 qualified studies on melatonin and 2 studies on REM sleep. Further analysis of these 15 reports indicated that a two-hour exposure to blue light (460 nm) in the evening suppresses melatonin, the maximum melatonin-suppressing effect being achieved at the shortest wavelengths (424 nm, violet). The melatonin concentration recovered rather rapidly, within 15 min from cessation of the exposure, suggesting a short-term or simultaneous impact of light exposure on the melatonin secretion. Melatonin secretion and suppression were reduced with age, but the light-induced circadian phase advance was not impaired with age. Light exposure in the evening, at night and in the morning affected the circadian phase of melatonin levels. In addition, even the longest wavelengths (631 nm, red) and intermittent light exposures induced circadian resetting responses, and exposure to low light levels (5-10 lux) at night when sleeping with eyes closed induced a circadian response. The review enables further development of an evaluation method of light pollution in LCA regarding the light-induced impacts on human circadian system.
https://pubmed.ncbi.nlm.nih.gov/30311830/
Light is necessary for life, and artificial light improves visual performance and safety, but there is an increasing concern of the potential health and environmental impacts of light. Findings from a number of studies suggest that mistimed light exposure disrupts the circadian rhythm in humans, potentially causing further health impacts. However, a variety of methods has been applied in individual experimental studies of light-induced circadian impacts, including definition of light exposure and outcomes. Thus, a systematic review is needed to synthesize the results. In addition, a review of the scientific evidence on the impacts of light on circadian rhythm is needed for developing an evaluation method of light pollution, i.e., the negative impacts of artificial light, in life cycle assessment (LCA). The current LCA practice does not have a method to evaluate the light pollution, neither in terms of human health nor the ecological impacts. The systematic literature survey was conducted by searching for two concepts: light and circadian rhythm. The circadian rhythm was searched with additional terms of melatonin and rapid-eye-movement (REM) sleep. The literature search resulted to 128 articles which were subjected to a data collection and analysis. Melatonin secretion was studied in 122 articles and REM sleep in 13 articles. The reports on melatonin secretion were divided into studies with specific light exposure (101 reports), usually in a controlled laboratory environment, and studies of prevailing light conditions typical at home or work environments (21 studies). Studies were generally conducted on adults in their twenties or thirties, but only very few studies experimented on children and elderly adults. Surprisingly many studies were conducted with a small sample size: 39 out of 128 studies were conducted with 10 or less subjects. The quality criteria of studies for more profound synthesis were a minimum sample size of 20 subjects and providing details of the light exposure (spectrum or wavelength; illuminance, irradiance or photon density). This resulted to 13 qualified studies on melatonin and 2 studies on REM sleep. Further analysis of these 15 reports indicated that a two-hour exposure to blue light (460 nm) in the evening suppresses melatonin, the maximum melatonin-suppressing effect being achieved at the shortest wavelengths (424 nm, violet). The melatonin concentration recovered rather rapidly, within 15 min from cessation of the exposure, suggesting a short-term or simultaneous impact of light exposure on the melatonin secretion. Melatonin secretion and suppression were reduced with age, but the light-induced circadian phase advance was not impaired with age. Light exposure in the evening, at night and in the morning affected the circadian phase of melatonin levels. In addition, even the longest wavelengths (631 nm, red) and intermittent light exposures induced circadian resetting responses, and exposure to low light levels (5-10 lux) at night when sleeping with eyes closed induced a circadian response. The review enables further development of an evaluation method of light pollution in LCA regarding the light-induced impacts on human circadian system.
https://pubmed.ncbi.nlm.nih.gov/30311830/
Lysets dæmpning af melatoninproduktionen hos mennesker er mere følsom end tidligere rapporteret
J Biol Rhythms. 2015 Aug;30(4):351-4. doi: 10.1177/0748730415585413. Epub 2015 May 27.Garen V Vartanian, Benjamin Y Li, Andrew P Chervenak, Olivia J Walch, Weston Pack, Petri Ala-Laurila, Kwoon Y WongPMID: 26017927 / PMCID: PMC4499476 / DOI: 10.1177/0748730415585413
Tidligere forskning viste, at hos mennesker er lysets dæmpning af melatonin mest følsomt over for 460 nm (blåt lys). Ved at bruge en protokol, der forbedrer datapræcisionen, har vi fundet...
Lysets dæmpning af melatoninproduktionen hos mennesker er mere følsom end tidligere rapporteret
Tidligere forskning viste, at hos mennesker er lysets dæmpning af melatonin mest følsomt over for 460 nm (blåt lys). Ved at bruge en protokol, der forbedrer datapræcisionen, har vi fundet tærsklen for human dæmpning af melatonin til at være ~10 logfotoner cm(-2) s(-1) ved 460 nm. Dette fund har vidtrækkende implikationer, da der er stigende beviser for, at natlig aktivering af det cirkadiske system kan være skadeligt.
Melatonin Suppression by Light in Humans Is More Sensitive Than Previously Reported
J Biol Rhythms. 2015 Aug;30(4):351-4. doi: 10.1177/0748730415585413. Epub 2015 May 27.
PMID: 26017927 / PMCID: PMC4499476 / DOI: 10.1177/0748730415585413
Abstract
The retina drives various non-image-forming photoresponses, including circadian photoentrainment and pupil constriction. Previous investigators showed that in humans, photic suppression of the clock-controlled hormone melatonin is most sensitive to 460-nm blue light, with a threshold of ~12 log photons cm(-2) s(-1). This threshold is surprising because non-image-forming vision is mediated by intrinsically photosensitive retinal ganglion cells, which receive rod-driven synaptic input and can respond to light levels as low as ~7 log photons cm(-2) s(-1). Using a protocol that enhances data precision, we have found the threshold for human melatonin suppression to be ~10 log photons cm(-2) s(-1) at 460 nm. This finding has far-reaching implications since there is mounting evidence that nocturnal activation of the circadian system can be harmful.
https://pubmed.ncbi.nlm.nih.gov/26017927/
The retina drives various non-image-forming photoresponses, including circadian photoentrainment and pupil constriction. Previous investigators showed that in humans, photic suppression of the clock-controlled hormone melatonin is most sensitive to 460-nm blue light, with a threshold of ~12 log photons cm(-2) s(-1). This threshold is surprising because non-image-forming vision is mediated by intrinsically photosensitive retinal ganglion cells, which receive rod-driven synaptic input and can respond to light levels as low as ~7 log photons cm(-2) s(-1). Using a protocol that enhances data precision, we have found the threshold for human melatonin suppression to be ~10 log photons cm(-2) s(-1) at 460 nm. This finding has far-reaching implications since there is mounting evidence that nocturnal activation of the circadian system can be harmful.
https://pubmed.ncbi.nlm.nih.gov/26017927/
Beskyttelse af melatoninrytmen gennem døgnrytme via sund lyseksponering
Int J Mol Sci. 2014 Dec 17;15(12):23448-500. doi: 10.3390/ijms151223448.Maria Angeles Bonmati-Carrion, Raquel Arguelles-Prieto, Maria Jose Martinez-Madrid, Russel Reiter, Ruediger Hardeland, Maria Angeles Rol, Juan Antonio MadridPMID: 25526564 / PMCID: PMC4284776 / DOI: 10.3390/ijms151223448
Epidemiologiske undersøgelser viser, at døgnrytmeforstyrrelser er forbundet med en øget forekomst af diabetes, fedme, hjertesygdomme, kognitiv og affektiv svækkelse, for tidlig aldring og nogle typer kræft. Blåt lys, som er særligt...
Beskyttelse af melatoninrytmen gennem døgnrytme via sund lyseksponering
Epidemiologiske undersøgelser viser, at døgnrytmeforstyrrelser er forbundet med en øget forekomst af diabetes, fedme, hjertesygdomme, kognitiv og affektiv svækkelse, for tidlig aldring og nogle typer kræft. Blåt lys, som er særligt gavnligt i dagtimerne, ser ud til at være mere forstyrrende om natten og fremkalder den stærkeste melatoninhæmning. Den natlige eksponering for blåt lys er i øjeblikket stigende på grund af udbredelsen af energieffektiv belysning (LED'er) og elektroniske enheder.
Protecting the melatonin rhythm through circadian healthy light exposure
Int J Mol Sci. 2014 Dec 17;15(12):23448-500. doi: 10.3390/ijms151223448.
PMID: 25526564 / PMCID: PMC4284776 / DOI: 10.3390/ijms151223448
Abstract
Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system.
https://pubmed.ncbi.nlm.nih.gov/25526564/
Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system.
https://pubmed.ncbi.nlm.nih.gov/25526564/
Blåt lys fra lysemitterende dioder fremkalder en dosisafhængig undertrykkelse af melatonin hos mennesker
J Appl Physiol (1985). 2011 Mar;110(3):619-26. doi: 10.1152/japplphysiol.01413.2009. Epub 2010 Dec 16.Kathleen E West, Michael R Jablonski, Benjamin Warfield, Kate S Cecil, Mary James, Melissa A Ayers, James Maida, Charles Bowen, David H Sliney, Mark D Rollag, John P Hanifin, George C BrainardPMID: 21164152 / DOI: 10.1152/japplphysiol.01413.2009
Lys dæmper produktionen af melatonin hos mennesker, hvor den stærkeste reaktion forekommer i den kortbølgelængde del af spektret mellem 446 og 477 nm (blåt lys). Blåt lys har også vist...
Blåt lys fra lysemitterende dioder fremkalder en dosisafhængig undertrykkelse af melatonin hos mennesker
Lys dæmper produktionen af melatonin hos mennesker, hvor den stærkeste reaktion forekommer i den kortbølgelængde del af spektret mellem 446 og 477 nm (blåt lys). Blåt lys har også vist sig at være mere effektivt end lys med længere bølgelængde til at øge årvågenheden. En sammenligning af en middel dæmpning af melatonin med 4.000 K hvidt bredbånds fluorescerende lys, som i øjeblikket bruges i de fleste almindelige belysningsarmaturer, tyder på, at blåt LED-lys med smal båndbredde kan være stærkere end 4.000 K hvidt fluorescerende lys til at dæmpe produktionen af melatonin.
Blue light from light-emitting diodes elicits a dose-dependent suppression of melatonin in humans
J Appl Physiol (1985). 2011 Mar;110(3):619-26. doi: 10.1152/japplphysiol.01413.2009. Epub 2010 Dec 16.
PMID: 21164152 / DOI: 10.1152/japplphysiol.01413.2009
Abstract
Light suppresses melatonin in humans, with the strongest response occurring in the short-wavelength portion of the spectrum between 446 and 477 nm that appears blue. Blue monochromatic light has also been shown to be more effective than longer-wavelength light for enhancing alertness. Disturbed circadian rhythms and sleep loss have been described as risk factors for astronauts and NASA ground control workers, as well as civilians. Such disturbances can result in impaired alertness and diminished performance. Prior to exposing subjects to short-wavelength light from light-emitting diodes (LEDs) (peak λ = 469 nm; 1/2 peak bandwidth = 26 nm), the ocular safety exposure to the blue LED light was confirmed by an independent hazard analysis using the American Conference of Governmental Industrial Hygienists exposure limits. Subsequently, a fluence-response curve was developed for plasma melatonin suppression in healthy subjects (n = 8; mean age of 23.9 ± 0.5 years) exposed to a range of irradiances of blue LED light. Subjects with freely reactive pupils were exposed to light between 2:00 and 3:30 AM. Blood samples were collected before and after light exposures and quantified for melatonin. The results demonstrate that increasing irradiances of narrowband blue-appearing light can elicit increasing plasma melatonin suppression in healthy subjects (P < 0.0001). The data were fit to a sigmoidal fluence-response curve (R(2) = 0.99; ED(50) = 14.19 μW/cm(2)). A comparison of mean melatonin suppression with 40 μW/cm(2) from 4,000 K broadband white fluorescent light, currently used in most general lighting fixtures, suggests that narrow bandwidth blue LED light may be stronger than 4,000 K white fluorescent light for suppressing melatonin.
https://pubmed.ncbi.nlm.nih.gov/21164152/
Light suppresses melatonin in humans, with the strongest response occurring in the short-wavelength portion of the spectrum between 446 and 477 nm that appears blue. Blue monochromatic light has also been shown to be more effective than longer-wavelength light for enhancing alertness. Disturbed circadian rhythms and sleep loss have been described as risk factors for astronauts and NASA ground control workers, as well as civilians. Such disturbances can result in impaired alertness and diminished performance. Prior to exposing subjects to short-wavelength light from light-emitting diodes (LEDs) (peak λ = 469 nm; 1/2 peak bandwidth = 26 nm), the ocular safety exposure to the blue LED light was confirmed by an independent hazard analysis using the American Conference of Governmental Industrial Hygienists exposure limits. Subsequently, a fluence-response curve was developed for plasma melatonin suppression in healthy subjects (n = 8; mean age of 23.9 ± 0.5 years) exposed to a range of irradiances of blue LED light. Subjects with freely reactive pupils were exposed to light between 2:00 and 3:30 AM. Blood samples were collected before and after light exposures and quantified for melatonin. The results demonstrate that increasing irradiances of narrowband blue-appearing light can elicit increasing plasma melatonin suppression in healthy subjects (P < 0.0001). The data were fit to a sigmoidal fluence-response curve (R(2) = 0.99; ED(50) = 14.19 μW/cm(2)). A comparison of mean melatonin suppression with 40 μW/cm(2) from 4,000 K broadband white fluorescent light, currently used in most general lighting fixtures, suggests that narrow bandwidth blue LED light may be stronger than 4,000 K white fluorescent light for suppressing melatonin.
https://pubmed.ncbi.nlm.nih.gov/21164152/
Bølgelængdeafhængige effekter ved udsættelse for lys om aftenen på søvnstruktur og søvn-EEG-effekttæthed hos mænd
Am J Physiol Regul Integr Comp Physiol. 2006 May;290(5):R1421-8. doi: 10.1152/ajpregu.00478.2005. Epub 2006 Jan 26.Mirjam Münch, Szymon Kobialka, Roland Steiner, Peter Oelhafen, Anna Wirz-Justice, Christian CajochenPMID: 16439671 / DOI: 10.1152/ajpregu.00478.2005
Vi testede virkningen af lys ved kort bølgelængde (460 nm) på søvn-EEG-effektspektre og søvnstruktur. Desuden forkortede blåt lys markant søvnvarigheden for hurtig øjenbevægelse (REM) under disse to søvncyklusser. Således var...
Bølgelængdeafhængige effekter ved udsættelse for lys om aftenen på søvnstruktur og søvn-EEG-effekttæthed hos mænd
Vi testede virkningen af lys ved kort bølgelængde (460 nm) på søvn-EEG-effektspektre og søvnstruktur. Desuden forkortede blåt lys markant søvnvarigheden for hurtig øjenbevægelse (REM) under disse to søvncyklusser. Således var lyseffekterne på dynamikken af SWA- og REM-søvnvarigheder blåforskydne i forhold til det visuelle fotopiske system med tre kegle, sandsynligvis medieret af døgnrytmen. Vores resultater kan tolkes i form af en induktion af en faseforsinkelse i døgnrytmen og/eller konsekvenser af en stærkere alarmerende effekt efter blåt lys, der fortsætter ind i søvnfasen.
Wavelength-dependent effects of evening light exposure on sleep architecture and sleep EEG power density in men
Am J Physiol Regul Integr Comp Physiol. 2006 May;290(5):R1421-8. doi: 10.1152/ajpregu.00478.2005. Epub 2006 Jan 26.
PMID: 16439671 / DOI: 10.1152/ajpregu.00478.2005
Abstract
Light strongly influences the circadian timing system in humans via non-image-forming photoreceptors in the retinal ganglion cells. Their spectral sensitivity is highest in the short-wavelength range of the visible light spectrum as demonstrated by melatonin suppression, circadian phase shifting, acute physiological responses, and subjective alertness. We tested the impact of short wavelength light (460 nm) on sleep EEG power spectra and sleep architecture. We hypothesized that its acute action on sleep is similar in magnitude to reported effects for polychromatic light at higher intensities and stronger than longer wavelength light (550 nm). The sleep EEGs of eight young men were analyzed after 2-h evening exposure to blue (460 nm) and green (550 nm) light of equal photon densities (2.8 x 10(13) photons x cm(-2) x s(-1)) and to dark (0 lux) under constant posture conditions. The time course of EEG slow-wave activity (SWA; 0.75-4.5 Hz) across sleep cycles after blue light at 460 nm was changed such that SWA was slightly reduced in the first and significantly increased during the third sleep cycle in parietal and occipital brain regions. Moreover, blue light significantly shortened rapid eye movement (REM) sleep duration during these two sleep cycles. Thus the light effects on the dynamics of SWA and REM sleep durations were blue shifted relative to the three-cone visual photopic system probably mediated by the circadian, non-image-forming visual system. Our results can be interpreted in terms of an induction of a circadian phase delay and/or repercussions of a stronger alerting effect after blue light, persisting into the sleep episode.
https://pubmed.ncbi.nlm.nih.gov/16439671/
Light strongly influences the circadian timing system in humans via non-image-forming photoreceptors in the retinal ganglion cells. Their spectral sensitivity is highest in the short-wavelength range of the visible light spectrum as demonstrated by melatonin suppression, circadian phase shifting, acute physiological responses, and subjective alertness. We tested the impact of short wavelength light (460 nm) on sleep EEG power spectra and sleep architecture. We hypothesized that its acute action on sleep is similar in magnitude to reported effects for polychromatic light at higher intensities and stronger than longer wavelength light (550 nm). The sleep EEGs of eight young men were analyzed after 2-h evening exposure to blue (460 nm) and green (550 nm) light of equal photon densities (2.8 x 10(13) photons x cm(-2) x s(-1)) and to dark (0 lux) under constant posture conditions. The time course of EEG slow-wave activity (SWA; 0.75-4.5 Hz) across sleep cycles after blue light at 460 nm was changed such that SWA was slightly reduced in the first and significantly increased during the third sleep cycle in parietal and occipital brain regions. Moreover, blue light significantly shortened rapid eye movement (REM) sleep duration during these two sleep cycles. Thus the light effects on the dynamics of SWA and REM sleep durations were blue shifted relative to the three-cone visual photopic system probably mediated by the circadian, non-image-forming visual system. Our results can be interpreted in terms of an induction of a circadian phase delay and/or repercussions of a stronger alerting effect after blue light, persisting into the sleep episode.
https://pubmed.ncbi.nlm.nih.gov/16439671/
Effekten af lys om aftenen på melatonin målt i spyttet hos japanske ungdomsskoleelever
J Circadian Rhythms. 2004 Aug 11;2(1):4. doi: 10.1186/1740-3391-2-4.Tetsuo HaradaPMID: 15304196 / PMCID: PMC515180 / DOI: 10.1186/1740-3391-2-4
Kraftigt lys på 2000 lux og selv moderate lys på 200-300 lux fra fluorescerende pærer kan hæmme natlig melatoninkoncentration hos unge mennesker. Lysstyrken fra et traditionel japansk ildsted, olielampe eller...
Effekten af lys om aftenen på melatonin målt i spyttet hos japanske ungdomsskoleelever
Kraftigt lys på 2000 lux og selv moderate lys på 200-300 lux fra fluorescerende pærer kan hæmme natlig melatoninkoncentration hos unge mennesker. Lysstyrken fra et traditionel japansk ildsted, olielampe eller stearinlys (20-30 lux) kunne være sundere for børn og unge, fordi en hurtig og tydelig stigning i melatoninkoncentrationen i blodet ser ud til at forekomme om natten under et så svagt lys, hvilket gør det lettere at falde i søvn.
Effects of evening light conditions on salivary melatonin of Japanese junior high school students
J Circadian Rhythms. 2004 Aug 11;2(1):4. doi: 10.1186/1740-3391-2-4.
PMID: 15304196 / PMCID: PMC515180 / DOI: 10.1186/1740-3391-2-4
Abstract
BACKGROUND: In a previous study, when adult subjects were exposed to a level of 400 lux light for more than 30 min or a level of 300 lux light for more than 2 hours, salivary melatonin concentration during the night dropped lower than when the subjects were exposed to dim illumination. It was suggested that such light exposure in adolescents or children during the first half of subjective night in normal life might decrease the melatonin level and prevent the falling into sleep. However, there has been no actual study on the effects of light exposure in adolescents. METHODS: Effects of exposure to the bright light (2000 lux) from fluorescent light bulbs during a period of three hours from 19:30 to 22:30 in one evening were examined on evening salivary melatonin concentrations from 19:45 to 23:40. The control group was exposed to dim light (60 lux) during these three hours. Both the dim light control group [DLCG] and the bright light experimental group [BLEG] consisted of two female and three male adolescent participants aged 14-15 y. RESULTS: The salivary melatonin level increased rapidly from 3.00 pg/ml at 21:45 to 9.18 pg/ml at 23:40 in DLCG, whereas it remained at less than 1.3 pg/ml for the three hours in BLEG. Melatonin concentration by BLEG at 22:30 of the experimental day was lower than that at the same time on the day before the experimental day, whereas it was significantly higher in the experimental day than on the day before the experimental day in DLCG. CONCLUSIONS: Bright lights of 2000 lux and even moderate lights of 200-300 lux from fluorescent light bulbs can inhibit nocturnal melatonin concentration in adolescents. Ancient Japanese lighting from a traditional Japanese hearth, oil lamp or candle (20-30 lux) could be healthier for children and adolescents because rapid and clear increase in melatonin concentration in blood seems to occur at night under such dim light, thus facilitating a smooth falling into night sleep.
https://pubmed.ncbi.nlm.nih.gov/15304196/
BACKGROUND: In a previous study, when adult subjects were exposed to a level of 400 lux light for more than 30 min or a level of 300 lux light for more than 2 hours, salivary melatonin concentration during the night dropped lower than when the subjects were exposed to dim illumination. It was suggested that such light exposure in adolescents or children during the first half of subjective night in normal life might decrease the melatonin level and prevent the falling into sleep. However, there has been no actual study on the effects of light exposure in adolescents. METHODS: Effects of exposure to the bright light (2000 lux) from fluorescent light bulbs during a period of three hours from 19:30 to 22:30 in one evening were examined on evening salivary melatonin concentrations from 19:45 to 23:40. The control group was exposed to dim light (60 lux) during these three hours. Both the dim light control group [DLCG] and the bright light experimental group [BLEG] consisted of two female and three male adolescent participants aged 14-15 y. RESULTS: The salivary melatonin level increased rapidly from 3.00 pg/ml at 21:45 to 9.18 pg/ml at 23:40 in DLCG, whereas it remained at less than 1.3 pg/ml for the three hours in BLEG. Melatonin concentration by BLEG at 22:30 of the experimental day was lower than that at the same time on the day before the experimental day, whereas it was significantly higher in the experimental day than on the day before the experimental day in DLCG. CONCLUSIONS: Bright lights of 2000 lux and even moderate lights of 200-300 lux from fluorescent light bulbs can inhibit nocturnal melatonin concentration in adolescents. Ancient Japanese lighting from a traditional Japanese hearth, oil lamp or candle (20-30 lux) could be healthier for children and adolescents because rapid and clear increase in melatonin concentration in blood seems to occur at night under such dim light, thus facilitating a smooth falling into night sleep.
https://pubmed.ncbi.nlm.nih.gov/15304196/
Tilpasning af menneskets melatoninproduktion med lys
J Clin Endocrinol Metab. 2004 Jul;89(7):3610-4. doi: 10.1210/jc.2003-032100.Kurt A Smith, Martin W Schoen, Charles A CzeislerPMID: 15240654 / DOI: 10.1210/jc.2003-032100 / J Clin Endocrinol Metab. 2005 Mar;90(3):1370
Den menneskelige indre ur styrer af frigivelsen af pinealhormonet melatonin, som fremmer søvn, sænker kropstemperaturen og mindsker kognitiv ydeevne. Vi fandt en signifikant stigning i dæmpningen af melatonin under stimulus...
Tilpasning af menneskets melatoninproduktion med lys
Den menneskelige indre ur styrer af frigivelsen af pinealhormonet melatonin, som fremmer søvn, sænker kropstemperaturen og mindsker kognitiv ydeevne. Vi fandt en signifikant stigning i dæmpningen af melatonin under stimulus ved cirka 0,5 lux sammenlignet med cirka 200 lux, hvilket afslørede, at mennesker udviser tilpasning af døgnrytmen ved lys.
Adaptation of human pineal melatonin suppression by recent photic history
J Clin Endocrinol Metab. 2004 Jul;89(7):3610-4. doi: 10.1210/jc.2003-032100.
PMID: 15240654 / DOI: 10.1210/jc.2003-032100 / J Clin Endocrinol Metab. 2005 Mar;90(3):1370
Abstract
The human circadian pacemaker controls the timing of the release of the pineal hormone melatonin, which promotes sleep, decreases body temperature, and diminishes cognitive performance. Abnormal melatonin secretion has been observed in psychiatric and circadian disorders. Although melatonin secretion is directly suppressed by exposure to light in a nonlinear intensity-dependent fashion, little research has focused on the effect of prior photic history on this response. We examined eight subjects in controlled laboratory conditions using a within-subjects design. Baseline melatonin secretion was monitored under constant routine conditions and compared with two additional constant routines with a fixed light stimulus for 6.5 h of 200 lux (50 microW/cm(2)) after approximately 3 d of photic exposure during the subjective day of either about 200 lux (50 microW/cm(2)) or about 0.5 lux (0.15 microW/cm(2)). We found a significant increase in melatonin suppression during the stimulus after a prior photic history of approximately 0.5 lux compared with approximately 200 lux, revealing that humans exhibit adaptation of circadian photoreception. Such adaptation indicates that translation of a photic stimulus into drive on the human circadian pacemaker involves more complex temporal dynamics than previously recognized. Further elucidation of these properties could prove useful in potentiating light therapies for circadian and affective disorders.
https://pubmed.ncbi.nlm.nih.gov/15240654/
The human circadian pacemaker controls the timing of the release of the pineal hormone melatonin, which promotes sleep, decreases body temperature, and diminishes cognitive performance. Abnormal melatonin secretion has been observed in psychiatric and circadian disorders. Although melatonin secretion is directly suppressed by exposure to light in a nonlinear intensity-dependent fashion, little research has focused on the effect of prior photic history on this response. We examined eight subjects in controlled laboratory conditions using a within-subjects design. Baseline melatonin secretion was monitored under constant routine conditions and compared with two additional constant routines with a fixed light stimulus for 6.5 h of 200 lux (50 microW/cm(2)) after approximately 3 d of photic exposure during the subjective day of either about 200 lux (50 microW/cm(2)) or about 0.5 lux (0.15 microW/cm(2)). We found a significant increase in melatonin suppression during the stimulus after a prior photic history of approximately 0.5 lux compared with approximately 200 lux, revealing that humans exhibit adaptation of circadian photoreception. Such adaptation indicates that translation of a photic stimulus into drive on the human circadian pacemaker involves more complex temporal dynamics than previously recognized. Further elucidation of these properties could prove useful in potentiating light therapies for circadian and affective disorders.
https://pubmed.ncbi.nlm.nih.gov/15240654/
Forholdet mellem indtræden af det svage lys for melatonin og søvn på en regelmæssig døgnrytme hos unge raske voksne
Behav Sleep Med. 2003;1(2):102-14. doi: 10.1207/S15402010BSM0102_3.Helen J Burgess, Natasha Savic, Tracey Sletten, Gregory Roach, Saul S Gilbert, Drew DawsonPMID: 15600132 / DOI: 10.1207/S15402010BSM0102_3
Vi undersøgte forholdet mellem den endogene melatonin-debut i svagt lys og søvntider hos 16 unge raske individer, som sov på deres sædvanlige tidspunkter i en uge. Den endogene melatonin-debut i...
Forholdet mellem indtræden af det svage lys for melatonin og søvn på en regelmæssig døgnrytme hos unge raske voksne
Vi undersøgte forholdet mellem den endogene melatonin-debut i svagt lys og søvntider hos 16 unge raske individer, som sov på deres sædvanlige tidspunkter i en uge. Den endogene melatonin-debut i svagt lys opstod omkring 2 timer før sengetid og 14 timer efter vækning. Vågentid og søvnens midtpunkt var signifikant forbundet med den endogene melatonin-debut i svagt lys, men det var det ikke ved sengetid. Muligheden for at forudsige unge raske menneskers endogene melatonin-debut i svagt lys ud fra deres søvntider diskuteres.
The relationship between the dim light melatonin onset and sleep on a regular schedule in young healthy adults
Behav Sleep Med. 2003;1(2):102-14. doi: 10.1207/S15402010BSM0102_3.
PMID: 15600132 / DOI: 10.1207/S15402010BSM0102_3
Abstract
The endogenous melatonin onset in dim light (DLMO) is a marker of circadian phase that can be used to appropriately time the administration of bright light or exogenous melatonin in order to elicit a desired phase shift. Determining an individual's circadian phase can be costly and time-consuming. We examined the relationship between the DLMO and sleep times in 16 young healthy individuals who slept at their habitual times for a week. The DLMO occurred about 2 hours before bedtime and 14 hours after wake. Wake time and midpoint of sleep were significantly associated with the DLMO (r = 0.77, r = 0.68 respectively), but bedtime was not (r = 0.36). The possibility of predicting young healthy normally entrained people's DLMOs from their sleep times is discussed.
https://pubmed.ncbi.nlm.nih.gov/15600132/
The endogenous melatonin onset in dim light (DLMO) is a marker of circadian phase that can be used to appropriately time the administration of bright light or exogenous melatonin in order to elicit a desired phase shift. Determining an individual's circadian phase can be costly and time-consuming. We examined the relationship between the DLMO and sleep times in 16 young healthy individuals who slept at their habitual times for a week. The DLMO occurred about 2 hours before bedtime and 14 hours after wake. Wake time and midpoint of sleep were significantly associated with the DLMO (r = 0.77, r = 0.68 respectively), but bedtime was not (r = 0.36). The possibility of predicting young healthy normally entrained people's DLMOs from their sleep times is discussed.
https://pubmed.ncbi.nlm.nih.gov/15600132/
Lysspektrum for melatoninundertrykkelse: bevis for et nyt ikke-stav, ikke-keglefotoreceptorsystem hos mennesker
J Physiol. 2001 Aug 15;535(Pt 1):261-7. doi: 10.1111/j.1469-7793.2001.t01-1-00261.x.K Thapan, J Arendt, D J SkenePMID: 11507175 / PMCID: PMC2278766 / DOI: 10.1111/j.1469-7793.2001.t01-1-00261.x
Vi ville undersøge de retinale fotopigmenters spektrale følsomhed for at frembringe en reaktion fra lysspektret. Tilpasning af en række fotopigmenter i området 420-480 nm viste, at rhodopsin-skabeloner mellem lambda(max) 457 og...
Lysspektrum for melatoninundertrykkelse: bevis for et nyt ikke-stav, ikke-keglefotoreceptorsystem hos mennesker
Vi ville undersøge de retinale fotopigmenters spektrale følsomhed for at frembringe en reaktion fra lysspektret. Tilpasning af en række fotopigmenter i området 420-480 nm viste, at rhodopsin-skabeloner mellem lambda(max) 457 og 462 nm passede godt til dataene (r(2) > eller =0,73) . Af disse var den bedste tilpasning til rhodopsin-skabelonen med lambda(max) 459 nm (r(2) = 0,74). 5. Vores data understøtter stærkt en primær rolle for et nyt kortbølgelængde fotopigment i lysinduceret melatoninundertrykkelse og giver det første direkte bevis på et fotoreceptivt system hos mennesker.
An action spectrum for melatonin suppression: evidence for a novel non-rod, non-cone photoreceptor system in humans
J Physiol. 2001 Aug 15;535(Pt 1):261-7. doi: 10.1111/j.1469-7793.2001.t01-1-00261.x.
PMID: 11507175 / PMCID: PMC2278766 / DOI: 10.1111/j.1469-7793.2001.t01-1-00261.x
Abstract
1. Non-image forming, irradiance-dependent responses mediated by the human eye include synchronisation of the circadian axis and suppression of pineal melatonin production. The retinal photopigment(s) transducing these light responses in humans have not been characterised. 2. Using the ability of light to suppress nocturnal melatonin production, we aimed to investigate its spectral sensitivity and produce an action spectrum. Melatonin suppression was quantified in 22 volunteers in 215 light exposure trials using monochromatic light (30 min pulse administered at circadian time (CT) 16-18) of different wavelengths (lambda(max) 424, 456, 472, 496, 520 and 548 nm) and irradiances (0.7-65.0 microW cm(-2)). 3. At each wavelength, suppression of plasma melatonin increased with increasing irradiance. Irradiance-response curves (IRCs) were fitted and the generated half-maximal responses (IR(50)) were corrected for lens filtering and used to construct an action spectrum. 4. The resulting action spectrum showed unique short-wavelength sensitivity very different from the classical scotopic and photopic visual systems. The lack of fit (r(2) < 0.1) of our action spectrum with the published rod and cone absorption spectra precluded these photoreceptors from having a major role. Cryptochromes 1 and 2 also had a poor fit to the data. Fitting a series of Dartnall nomograms generated for rhodopsin-based photopigments over the lambda(max) range 420-480 nm showed that rhodopsin templates between lambda(max) 457 and 462 nm fitted the data well (r(2) > or =0.73). Of these, the best fit was to the rhodopsin template with lambda(max) 459 nm (r(2) = 0.74). 5. Our data strongly support a primary role for a novel short-wavelength photopigment in light-induced melatonin suppression and provide the first direct evidence of a non-rod, non-cone photoreceptive system in humans.
https://pubmed.ncbi.nlm.nih.gov/11507175/
1. Non-image forming, irradiance-dependent responses mediated by the human eye include synchronisation of the circadian axis and suppression of pineal melatonin production. The retinal photopigment(s) transducing these light responses in humans have not been characterised. 2. Using the ability of light to suppress nocturnal melatonin production, we aimed to investigate its spectral sensitivity and produce an action spectrum. Melatonin suppression was quantified in 22 volunteers in 215 light exposure trials using monochromatic light (30 min pulse administered at circadian time (CT) 16-18) of different wavelengths (lambda(max) 424, 456, 472, 496, 520 and 548 nm) and irradiances (0.7-65.0 microW cm(-2)). 3. At each wavelength, suppression of plasma melatonin increased with increasing irradiance. Irradiance-response curves (IRCs) were fitted and the generated half-maximal responses (IR(50)) were corrected for lens filtering and used to construct an action spectrum. 4. The resulting action spectrum showed unique short-wavelength sensitivity very different from the classical scotopic and photopic visual systems. The lack of fit (r(2) < 0.1) of our action spectrum with the published rod and cone absorption spectra precluded these photoreceptors from having a major role. Cryptochromes 1 and 2 also had a poor fit to the data. Fitting a series of Dartnall nomograms generated for rhodopsin-based photopigments over the lambda(max) range 420-480 nm showed that rhodopsin templates between lambda(max) 457 and 462 nm fitted the data well (r(2) > or =0.73). Of these, the best fit was to the rhodopsin template with lambda(max) 459 nm (r(2) = 0.74). 5. Our data strongly support a primary role for a novel short-wavelength photopigment in light-induced melatonin suppression and provide the first direct evidence of a non-rod, non-cone photoreceptive system in humans.
https://pubmed.ncbi.nlm.nih.gov/11507175/
Lysspekter for melatoninregulering hos mennesker: beviser for en ny cirkadisk fotoreceptor
J Neurosci. 2001 Aug 15;21(16):6405-12. doi: 10.1523/JNEUROSCI.21-16-06405.2001.G C Brainard, J P Hanifin, J M Greeson, B Byrne, G Glickman, E Gerner, M D RollagPMID: 11487664 / PMCID: PMC6763155 / DOI: 10.1523/JNEUROSCI.21-16-06405.2001
Denne undersøgelse skulle belyse det okulære fotoreceptorsystem til regulering af den menneskelige pinealkirtel. Handlingsspektret konstrueret ud fra disse data passer til en opsin-skabelon (R(2) = 0,91), som identificerer 446-477 nm som...
Lysspekter for melatoninregulering hos mennesker: beviser for en ny cirkadisk fotoreceptor
Denne undersøgelse skulle belyse det okulære fotoreceptorsystem til regulering af den menneskelige pinealkirtel. Handlingsspektret konstrueret ud fra disse data passer til en opsin-skabelon (R(2) = 0,91), som identificerer 446-477 nm som den mest potente bølgelængderegion, der giver cirkadisk input til regulering af melatoninsekretion. Et enkelt fotopigment hos mennesker kan være primært ansvarligt for melatoninundertrykkelse. Disse resultater tyder på, at der er et nyt opsin-fotopigment i det menneskelige øje, der medierer døgnrytmefotoreception.
Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor
J Neurosci. 2001 Aug 15;21(16):6405-12. doi: 10.1523/JNEUROSCI.21-16-06405.2001.
PMID: 11487664 / PMCID: PMC6763155 / DOI: 10.1523/JNEUROSCI.21-16-06405.2001
Abstract
The photopigment in the human eye that transduces light for circadian and neuroendocrine regulation, is unknown. The aim of this study was to establish an action spectrum for light-induced melatonin suppression that could help elucidate the ocular photoreceptor system for regulating the human pineal gland. Subjects (37 females, 35 males, mean age of 24.5 +/- 0.3 years) were healthy and had normal color vision. Full-field, monochromatic light exposures took place between 2:00 and 3:30 A.M. while subjects' pupils were dilated. Blood samples collected before and after light exposures were quantified for melatonin. Each subject was tested with at least seven different irradiances of one wavelength with a minimum of 1 week between each nighttime exposure. Nighttime melatonin suppression tests (n = 627) were completed with wavelengths from 420 to 600 nm. The data were fit to eight univariant, sigmoidal fluence-response curves (R(2) = 0.81-0.95). The action spectrum constructed from these data fit an opsin template (R(2) = 0.91), which identifies 446-477 nm as the most potent wavelength region providing circadian input for regulating melatonin secretion. The results suggest that, in humans, a single photopigment may be primarily responsible for melatonin suppression, and its peak absorbance appears to be distinct from that of rod and cone cell photopigments for vision. The data also suggest that this new photopigment is retinaldehyde based. These findings suggest that there is a novel opsin photopigment in the human eye that mediates circadian photoreception.
https://pubmed.ncbi.nlm.nih.gov/11487664/
The photopigment in the human eye that transduces light for circadian and neuroendocrine regulation, is unknown. The aim of this study was to establish an action spectrum for light-induced melatonin suppression that could help elucidate the ocular photoreceptor system for regulating the human pineal gland. Subjects (37 females, 35 males, mean age of 24.5 +/- 0.3 years) were healthy and had normal color vision. Full-field, monochromatic light exposures took place between 2:00 and 3:30 A.M. while subjects' pupils were dilated. Blood samples collected before and after light exposures were quantified for melatonin. Each subject was tested with at least seven different irradiances of one wavelength with a minimum of 1 week between each nighttime exposure. Nighttime melatonin suppression tests (n = 627) were completed with wavelengths from 420 to 600 nm. The data were fit to eight univariant, sigmoidal fluence-response curves (R(2) = 0.81-0.95). The action spectrum constructed from these data fit an opsin template (R(2) = 0.91), which identifies 446-477 nm as the most potent wavelength region providing circadian input for regulating melatonin secretion. The results suggest that, in humans, a single photopigment may be primarily responsible for melatonin suppression, and its peak absorbance appears to be distinct from that of rod and cone cell photopigments for vision. The data also suggest that this new photopigment is retinaldehyde based. These findings suggest that there is a novel opsin photopigment in the human eye that mediates circadian photoreception.
https://pubmed.ncbi.nlm.nih.gov/11487664/