Abstract
Circadian adaptation to night work usually does not occur in naturalistic conditions, largely due to exposure to low levels of light during the night and light in the morning on the way home. This leads to circadian misalignment, which has documented deleterious effects on sleep and functioning during waking hours. Chronic circadian misalignment is also being increasingly associated with long-term health comorbidities. As the circadian system is mostly sensitive to short wavelengths (i.e., blue light) and less sensitive to long wavelengths (i.e., red light), shaping light exposure in a "wavelength-wise" manner has been proposed to promote partial adaptation to night shifts, and, therefore, alleviate circadian rhythms disruption. This report presents results from two cross-over designed studies that aimed to investigate the effects of three different light conditions on circadian phase, sleepiness, and alertness of police patrol officers on a rotating shift schedule. The first study took place during summer (n = 15) and the second study (n = 25) during winter/early spring. In both studies, all participants went through three conditions composed of four consecutive night shifts: 1) in-car dim blue light exposure during the night shift and wearing of blue-blocking glasses (BBG) in the morning after 05:00 h; 2) in-car red light exposure during the night shift and wearing of BBG in the morning after 05:00 h; 3) a control condition with no intervention. To assess circadian phase position, salivary melatonin was collected hourly the night before and the night after each condition. Sleep was monitored by wrist actigraphy. Also, a 10-min Psychomotor Vigilance-Task was administered at the beginning and end of each night shift and the Karolinska Sleepiness Scale was completed every 2 h during each night shift. In the summer study, no difference was found in alertness and sleepiness between conditions. Participants though exhibited greater (≈3 h) phase delay after four consecutive night shifts in the control condition (in which morning light exposure was expected to prevent phase delay) than after the blue and red conditions (≈2 h) (in which wearing BBG were expected to promote phase delay). In the second study performed during the winter/early spring, a comparable ≈2 h phase delay was found in each of the three conditions, with no difference in alertness and sleepiness between conditions. In conclusion, participants in both studies exhibited modest phase delay across the four night shifts, even during the control conditions. Still, re-entrainment was not fast enough to produce partial circadian adaptation after four night shifts. A greater number of consecutive night shifts may be necessary to produce enough circadian alignment to elicit benefits on sleepiness and alertness in workers driving a motorized vehicle during night shifts. In-car dim blue light exposure combined with the wearing of BBG in the morning did not show the expected benefits on circadian adaptation, sleepiness, and alertness in our studies. Higher levels of light may be warranted when implementing light intervention in a motorized vehicle setting.
https://pubmed.ncbi.nlm.nih.gov/33588653/
Skifteholdsarbejde
Natarbejdere skal – ligesom folk, der arbejder om dagen – udføre opgaver, som kræver opmærksomhed, fornuftige konklusioner, beslutsomhed og andre mentale evner. I lighed med alle andre skal natarbejdere præstere og skabe succes på deres arbejde. Rigtig mange mennesker inden for mange forskellige brancher arbejder om natten – eller sent om aftenen, hvilket også kan forstyrre døgnrytmen. Det gælder f.eks. fabriksansatte, skuespillere, musikere, TV-ansatte, programmører, journalister, læger, sygeplejersker, diplomater og virksomhedsledere. De arbejder alle ofte sent og uregelmæssigt.
Beskrivelse
Skifteholdsarbejde og søvn
Mennesker, der lever efter en normal døgnrytme, er vågne om dagen og sover om natten.
Men i modsætning til de fleste mennesker, der arbejder om dagen, kæmper natarbejdere ikke alene for at klare de udfordringer, der altid følger med et job. De bekæmper også den træthed, som kroppen – via den naturlige melatoninproduktion – bliver overvældet af, når det er mørkt udenfor.
Personer, der arbejder om natten, har typisk brug for en uges tid for at vende tilbage til den normale døgnrytme, fx i forbindelse med weekender, ferier og fridage.
Døgnrytmen reguleres af hjernens "indre ur", som påvirkes af lys, der opfanges af øjets nethinde. Det indre ur regulerer blandt andet produktionen af signalstoffet melatonin, der produceres i hjernens koglekirtel om natten. Hvis det indre ur udsættes for lys om natten, hæmmes produktionen af melatonin.
Skifteholdsarbejde og søvnbriller
En kombination af søvnbriller og lysterapi kan hjælpe natarbejdere med at regulere deres døgnrytme og søvnmønster, så de kan sove ordentligt om dagen og kan føle sig friske og velforberedte til natarbejde.
Hvis man arbejder, fx fra kl. 23:00 til kl. 7:00, er det en rigtig god idé at få lysterapi - fx via en lysterapilampe eller et lysvisir - inden man kommer på arbejde. Så tænker kroppen, at den skal være vågen. Ydermere er det en stor fordel, hvis det er muligt at fortsætte lysterapien under arbejdet. Det skarpe lys holder skifteholdsarbejdere vågen, da det indeholder blåt lys, som hæmmer produktionen af melatonin.
Så snart man har fri fra natarbejde, skal man iføres sig søvnbriller, som blokerer for alt det blå lys. Dermed øges produktionen af melatonin, og det er efterfølgende nemmere at falde i søvn.
Skal man f.eks. sove fra kl. 9:00 til 17:00, bør man iføre sig søvnbrillerne, så snart man har fri fra natarbejde. Søvnbrillerne får kroppen til at sætte farten ned og gøre sig klar til at sove. Når man vågner kl. 17:00, bør man få lysterapi i ca. 30 minutter for at nulstille døgnrytmen. Og så starter det forfra.
Både menneskeliv og store pengesummer kan spares ved at indføre tiltag, der tager hensyn til den menneskelige døgnrytme. I de kommende år bliver det en stor udfordring for virksomheder og institutioner at indføre disse tiltag.
Forskning vedrørende skifteholdsarbejde
Brug af søvnbriller og blåt lys i bilen på vej hjem fra skifteholdsarbejde om morgenen forbedrer ikke tilpasning af døgnrytmen ved hyppigt roterende skifteholdsarbejde
Chronobiol Int. 2021 May;38(5):705-719. doi: 10.1080/07420528.2021.1872592. Epub 2021 Feb 15.Jeanne Sophie Martin, Luc Laberge, Alexandre Sasseville, Marilie Bérubé, Samuel Alain, Joëlle Lavoie, Jérôme Houle, Marc HébertPMID: 33588653 / DOI: 10.1080/07420528.2021.1872592
Denne rapport havde til formål at undersøge virkningerne af tre forskellige lysforhold på døgnfasen, søvnighed og årvågenhed hos politibetjente på en roterende vagtplan. Som konklusion udviste deltagere i begge undersøgelser beskeden...
Brug af søvnbriller og blåt lys i bilen på vej hjem fra skifteholdsarbejde om morgenen forbedrer ikke tilpasning af døgnrytmen ved hyppigt roterende skifteholdsarbejde
Denne rapport havde til formål at undersøge virkningerne af tre forskellige lysforhold på døgnfasen, søvnighed og årvågenhed hos politibetjente på en roterende vagtplan. Som konklusion udviste deltagere i begge undersøgelser beskeden faseforsinkelse på tværs af de fire nattevagter. Et større antal på hinanden følgende nattevagter kan være nødvendigt for at omstille døgnrytmen. Eksponering for dæmpet blåt lys i bilen kombineret med brug af søvnbriller om morgenen viste ikke de forventede fordele mht. døgnrytmetilpasning, søvnighed og årvågenhed. En stærkere lysstyrke kan være nødvendigt, for at fremvise et bedre resultat.
Timely use of in-car dim blue light and blue blockers in the morning does not improve circadian adaptation of fast rotating shift workers
Chronobiol Int. 2021 May;38(5):705-719. doi: 10.1080/07420528.2021.1872592. Epub 2021 Feb 15.
PMID: 33588653 / DOI: 10.1080/07420528.2021.1872592
Søvnforstyrrelser blandt læger på skifteholdsarbejde
Anaesthesist. 2014 Nov;63(11):844-51. doi: 10.1007/s00101-014-2374-z.O Schlafer, V Wenzel, B HöglPMID: 25213642 / DOI: 10.1007/s00101-014-2374-z
Formålet med dette oplæg er, at undersøge mulige årsager, medvirkende faktorer og konsekvenser af søvnforstyrrelser hos læger. Efter endt skifteholdsarbejde kan direkte sollys på nethinden undgås ved at bruge mørke...
Søvnforstyrrelser blandt læger på skifteholdsarbejde
Formålet med dette oplæg er, at undersøge mulige årsager, medvirkende faktorer og konsekvenser af søvnforstyrrelser hos læger. Efter endt skifteholdsarbejde kan direkte sollys på nethinden undgås ved at bruge mørke solbriller eller søvnbriller til at pendle hjem. Hjemmemiljøet til dagssøvn efter en nattevagt bør være meget mørkt for at fremme udskillelse af endogen melatonin, som er et natsignal og understøtter kontinuerlig søvn. Træthed på grund af søvnmangel kan kun behandles systematisk med søvn.
Sleep disorders among physicians on shift work
Anaesthesist. 2014 Nov;63(11):844-51. doi: 10.1007/s00101-014-2374-z.
PMID: 25213642 / DOI: 10.1007/s00101-014-2374-z
Abstract
Sleep disorders in physicians who perform shift work can result in increased risks of health problems that negatively impact performance and patient safety. Even those who cope well with shift work are likely to suffer from sleep disorders. The aim of this manuscript is to discuss possible causes, contributing factors and consequences of sleep disorders in physicians and to identify measures that can improve adaptation to shift work and treatment strategies for shift work-associated sleep disorders. The risk factors that influence the development of sleep disorders in physicians are numerous and include genetic factors (15 % of the population), age (> 50 years), undiagnosed sleep apnea,, alcohol abuse as well as multiple stress factors inherent in clinical duties (including shift work), research, teaching and family obligations. Several studies have reported an increased risk for medical errors in sleep-deprived physicians. Shift workers have an increased risk for psychiatric and cardiovascular diseases and shift work may also be a contributing factor to cancer. A relationship has been reported not only with sleep deprivation and changes in food intake but also with diabetes mellitus, obesity, hypertension and coronary heart disease. Nicotine and alcohol consumption are more frequent among shift workers. Increased sickness and accident rates among physicians when commuting (especially after night shifts) have a socioeconomic impact. In order to reduce fatigue and to improve performance, short naps during shiftwork or naps plus caffeine, have been proposed as coping strategies; however, napping during adverse circadian phases is less effective, if not impossible when unable to fall asleep. Bright and blue light supports alertness during a night shift. After shiftwork, direct sunlight exposure to the retina can be avoided by using dark sunglasses or glasses with orange lenses for commuting home. The home environment for daytime sleeping after a night shift should be very dark to allow endogenous melatonin secretion, which is a night signal and supports continuous sleep. Sleep disorders can be treated with timed light exposure, as well as behavioral and environmental strategies to compensate for sleep deprivation. Fatigue due to sleep deprivation can only be systematically treated with sleep.
https://pubmed.ncbi.nlm.nih.gov/25213642/
Sleep disorders in physicians who perform shift work can result in increased risks of health problems that negatively impact performance and patient safety. Even those who cope well with shift work are likely to suffer from sleep disorders. The aim of this manuscript is to discuss possible causes, contributing factors and consequences of sleep disorders in physicians and to identify measures that can improve adaptation to shift work and treatment strategies for shift work-associated sleep disorders. The risk factors that influence the development of sleep disorders in physicians are numerous and include genetic factors (15 % of the population), age (> 50 years), undiagnosed sleep apnea,, alcohol abuse as well as multiple stress factors inherent in clinical duties (including shift work), research, teaching and family obligations. Several studies have reported an increased risk for medical errors in sleep-deprived physicians. Shift workers have an increased risk for psychiatric and cardiovascular diseases and shift work may also be a contributing factor to cancer. A relationship has been reported not only with sleep deprivation and changes in food intake but also with diabetes mellitus, obesity, hypertension and coronary heart disease. Nicotine and alcohol consumption are more frequent among shift workers. Increased sickness and accident rates among physicians when commuting (especially after night shifts) have a socioeconomic impact. In order to reduce fatigue and to improve performance, short naps during shiftwork or naps plus caffeine, have been proposed as coping strategies; however, napping during adverse circadian phases is less effective, if not impossible when unable to fall asleep. Bright and blue light supports alertness during a night shift. After shiftwork, direct sunlight exposure to the retina can be avoided by using dark sunglasses or glasses with orange lenses for commuting home. The home environment for daytime sleeping after a night shift should be very dark to allow endogenous melatonin secretion, which is a night signal and supports continuous sleep. Sleep disorders can be treated with timed light exposure, as well as behavioral and environmental strategies to compensate for sleep deprivation. Fatigue due to sleep deprivation can only be systematically treated with sleep.
https://pubmed.ncbi.nlm.nih.gov/25213642/
Ændring af lysbølgelængder ved hjælp af søvnbriller: effekt på melatoninsekretion
Fertil Steril. 2014 Aug;102(2):336-8. doi: 10.1016/j.fertnstert.2014.06.006. Epub 2014 Jul 9.Robert F Casper, Shadab RahmanPMID: 25015557 / DOI: 10.1016/j.fertnstert.2014.06.006
Blokering af lys om morgenen med mørke briller kan bidrage til tilpasningen til natarbejde, men disse briller er uforenelige med kørsel. Vi testede hypotesen om, at bortfiltrering af det blå...
Ændring af lysbølgelængder ved hjælp af søvnbriller: effekt på melatoninsekretion
Blokering af lys om morgenen med mørke briller kan bidrage til tilpasningen til natarbejde, men disse briller er uforenelige med kørsel. Vi testede hypotesen om, at bortfiltrering af det blå lys i lysspektret med søvnbriller kan forhindre den lysinducerede melatoninundertrykkelse. Søvnbriller repræsenterer et elegant metode til at forhindre den lysinducerede melatoninundertrykkelse. Yderligere undersøgelser er nødvendige for at vise, at disse briller, som er velegnede til kørsel, kan lette tilpasningen til natarbejde.
Spectral modulation of light wavelengths using optical filters: effect on melatonin secretion
Fertil Steril. 2014 Aug;102(2):336-8. doi: 10.1016/j.fertnstert.2014.06.006. Epub 2014 Jul 9.
PMID: 25015557 / DOI: 10.1016/j.fertnstert.2014.06.006
Abstract
Shiftwork has been identified as a risk factor for various medical problems, such as cancer, heart disease, metabolic disturbances, depression, and anxiety disorders, and as reviewed this month, adverse reproductive function. Shiftwork misaligns physiological rhythms with respect to each other and to external environmental rhythms such as the 24-hour light/dark cycle. Light is the strongest time cue for entraining circadian rhythms in mammals, and aberrant light exposure patterns during shiftwork is one of the key factors that induce circadian misalignment. We have recently demonstrated, in both animal and clinical models, that filtering short wavelengths (below 480 nm) from nocturnal lighting can attenuate alterations in hormone secretion (melatonin and glucocorticoids) and in central and peripheral clock gene expression induced by nighttime light exposure. We also demonstrated that the use of optical filters led to an improvement in mood and in cognitive performance under controlled laboratory conditions and during field-based shiftwork studies. Moreover, there was an increase in sleep duration and quality on nights immediately following night shifts. We believe it is likely that optical filters incorporated into glasses or as coverings for light bulbs could be used as a method to improve or prevent many of the medical problems associated with circadian misalignment and rotating shiftwork.
https://pubmed.ncbi.nlm.nih.gov/25015557/
Shiftwork has been identified as a risk factor for various medical problems, such as cancer, heart disease, metabolic disturbances, depression, and anxiety disorders, and as reviewed this month, adverse reproductive function. Shiftwork misaligns physiological rhythms with respect to each other and to external environmental rhythms such as the 24-hour light/dark cycle. Light is the strongest time cue for entraining circadian rhythms in mammals, and aberrant light exposure patterns during shiftwork is one of the key factors that induce circadian misalignment. We have recently demonstrated, in both animal and clinical models, that filtering short wavelengths (below 480 nm) from nocturnal lighting can attenuate alterations in hormone secretion (melatonin and glucocorticoids) and in central and peripheral clock gene expression induced by nighttime light exposure. We also demonstrated that the use of optical filters led to an improvement in mood and in cognitive performance under controlled laboratory conditions and during field-based shiftwork studies. Moreover, there was an increase in sleep duration and quality on nights immediately following night shifts. We believe it is likely that optical filters incorporated into glasses or as coverings for light bulbs could be used as a method to improve or prevent many of the medical problems associated with circadian misalignment and rotating shiftwork.
https://pubmed.ncbi.nlm.nih.gov/25015557/
Søvnbriller hæmmer kapaciteten af stærkt lys til undertrykkelse af melatoninproduktionen
J Pineal Res. 2006 Aug;41(1):73-8. doi: 10.1111/j.1600-079X.2006.00332.x.Alexandre Sasseville, Nathalie Paquet, Jean Sévigny, Marc HébertPMID: 16842544 / DOI: 10.1111/j.1600-079X.2006.00332.x
Blokering af lys om morgenen med mørke briller kan bidrage til tilpasningen til natarbejde, men disse briller er uforenelige med kørsel. Vi testede hypotesen om, at bortfiltrering af det blå...
Søvnbriller hæmmer kapaciteten af stærkt lys til undertrykkelse af melatoninproduktionen
Blokering af lys om morgenen med mørke briller kan bidrage til tilpasningen til natarbejde, men disse briller er uforenelige med kørsel. Vi testede hypotesen om, at bortfiltrering af det blå lys i lysspektret med søvnbriller kan forhindre den lysinducerede melatoninundertrykkelse. Søvnbriller repræsenterer et elegant metode til at forhindre den lysinducerede melatoninundertrykkelse. Yderligere undersøgelser er nødvendige for at vise, at disse briller, som er velegnede til kørsel, kan lette tilpasningen til natarbejde.
Blue blocker glasses impede the capacity of bright light to suppress melatonin production
J Pineal Res. 2006 Aug;41(1):73-8. doi: 10.1111/j.1600-079X.2006.00332.x.
PMID: 16842544 / DOI: 10.1111/j.1600-079X.2006.00332.x
Abstract
Blocking morning light exposure with dark goggles can contribute to the adjustment to night work but these glasses are incompatible with driving. Recently, it was discovered that the biological clock is most sensitive to short wavelengths (blue light). Therefore, we tested the hypothesis that cutting the blue portion of the light spectrum with orange lens glasses (blue blockers) would prevent the light-induced melatonin suppression, a test broadly used as an indirect assessment of the circadian clock sensitivity. Fourteen normal subjects were exposed at night to a 60 min bright light pulse (1300 lx behind filters) between 01:00 and 02:00 hr while wearing orange lens glasses (experimental condition) or grey lens glasses (control condition). The amount of salivary melatonin change observed during the light pulse was compared with a melatonin baseline obtained the night before. Although both glasses transmitted the same illuminance (1300 lx) but at an irradiance 25% higher for the orange lens (408 microW/cm2) compared with the grey lens (327 microW/cm2), a non-significant increase of 6% (95% CI, -20% to 9%) was observed with the orange lens whereas a significant (P < 0.05) reduction of 46% (95% CI, 35-57%) was observed with the grey lens. Blue blockers represent an elegant means to prevent the light-induced melatonin suppression. Further studies are needed to show that these glasses, which are suitable for driving, could facilitate adaptation to night work.
https://pubmed.ncbi.nlm.nih.gov/16842544/
Blocking morning light exposure with dark goggles can contribute to the adjustment to night work but these glasses are incompatible with driving. Recently, it was discovered that the biological clock is most sensitive to short wavelengths (blue light). Therefore, we tested the hypothesis that cutting the blue portion of the light spectrum with orange lens glasses (blue blockers) would prevent the light-induced melatonin suppression, a test broadly used as an indirect assessment of the circadian clock sensitivity. Fourteen normal subjects were exposed at night to a 60 min bright light pulse (1300 lx behind filters) between 01:00 and 02:00 hr while wearing orange lens glasses (experimental condition) or grey lens glasses (control condition). The amount of salivary melatonin change observed during the light pulse was compared with a melatonin baseline obtained the night before. Although both glasses transmitted the same illuminance (1300 lx) but at an irradiance 25% higher for the orange lens (408 microW/cm2) compared with the grey lens (327 microW/cm2), a non-significant increase of 6% (95% CI, -20% to 9%) was observed with the orange lens whereas a significant (P < 0.05) reduction of 46% (95% CI, 35-57%) was observed with the grey lens. Blue blockers represent an elegant means to prevent the light-induced melatonin suppression. Further studies are needed to show that these glasses, which are suitable for driving, could facilitate adaptation to night work.
https://pubmed.ncbi.nlm.nih.gov/16842544/
Blokering af det blå lys forhindrer dæmpning af melatoninproduktion om natten uden negativ indvirkning på ydeevnen under simuleret skifteholdsarbejde
J Clin Endocrinol Metab. 2005 May;90(5):2755-61. doi: 10.1210/jc.2004-2062. Epub 2005 Feb 15.Leonid Kayumov, Robert F Casper, Raed J Hawa, Boris Perelman, Sharon A Chung, Steven Sokalsky, Colin M ShapiroPMID: 15713707 / DOI: 10.1210/jc.2004-2062
Fald i melatoninproduktionen hos mennesker og dyr er kendt for at være forårsaget af miljøbelysning, især det blå lys (mellem 470 og 525 nm). Vi undersøgte den nye hypotese om,...
Blokering af det blå lys forhindrer dæmpning af melatoninproduktion om natten uden negativ indvirkning på ydeevnen under simuleret skifteholdsarbejde
Fald i melatoninproduktionen hos mennesker og dyr er kendt for at være forårsaget af miljøbelysning, især det blå lys (mellem 470 og 525 nm). Vi undersøgte den nye hypotese om, at brugen af søvnbriller som udelukker alle bølgelængder mindre end 530 nm, kunne forhindre undertrykkelse af melatonin under stærkt lysforhold under et simuleret skifteholdseksperiment. Alle forsøgspersoner udviste stabile melatoninniveauer ved brug af søvnbriller, svarende til deres sekretionsprofil med svagt lys. Almindelig skarpt lys undertrykte drastisk melatoninproduktionen. Normalisering af endogen melatoninproduktion ved brug af søvnbriller forringede ikke målene for ydeevne, subjektiv søvnighed eller årvågenhed.
Blocking low-wavelength light prevents nocturnal melatonin suppression with no adverse effect on performance during simulated shift work
J Clin Endocrinol Metab. 2005 May;90(5):2755-61. doi: 10.1210/jc.2004-2062. Epub 2005 Feb 15.
PMID: 15713707 / DOI: 10.1210/jc.2004-2062
Abstract
Decreases in melatonin production in human and animals are known to be caused by environmental lighting, especially short-wavelength lighting (between 470 and 525 nm). We investigated the novel hypothesis that the use of goggles with selective exclusion of all wavelengths less than 530 nm could prevent the suppression of melatonin in bright-light conditions during a simulated shift-work experiment. Salivary melatonin levels were measured under dim (<5 lux), bright (800 lux), and filtered (800 lux) light at hourly intervals between 2000 and 0800 h in 11 healthy young males and eight females (mean age, 24.7 +/- 4.6 yr). The measurements were performed during three nonconsecutive nights over a 2-wk period. Subjective sleepiness was measured by self-report scales, whereas objective performance was assessed with the Continuous Performance Test. All subjects demonstrated preserved melatonin levels in filtered light similar to their dim-light secretion profile. Unfiltered bright light drastically suppressed melatonin production. Normalization of endogenous melatonin production while wearing goggles did not impair measures of performance, subjective sleepiness, or alertness.
https://pubmed.ncbi.nlm.nih.gov/15713707/
Decreases in melatonin production in human and animals are known to be caused by environmental lighting, especially short-wavelength lighting (between 470 and 525 nm). We investigated the novel hypothesis that the use of goggles with selective exclusion of all wavelengths less than 530 nm could prevent the suppression of melatonin in bright-light conditions during a simulated shift-work experiment. Salivary melatonin levels were measured under dim (<5 lux), bright (800 lux), and filtered (800 lux) light at hourly intervals between 2000 and 0800 h in 11 healthy young males and eight females (mean age, 24.7 +/- 4.6 yr). The measurements were performed during three nonconsecutive nights over a 2-wk period. Subjective sleepiness was measured by self-report scales, whereas objective performance was assessed with the Continuous Performance Test. All subjects demonstrated preserved melatonin levels in filtered light similar to their dim-light secretion profile. Unfiltered bright light drastically suppressed melatonin production. Normalization of endogenous melatonin production while wearing goggles did not impair measures of performance, subjective sleepiness, or alertness.
https://pubmed.ncbi.nlm.nih.gov/15713707/