Melatonin and light

Melatonin is a signalling substance found in all living beings: humans, animals and plants. Melatonin is called the body's natural sleep aid. This is because the substance stimulates sleep and sleep quality. Melatonin is also a powerful antioxidant, which strengthens the immune system and helps to protect the body's cells and tissues. In addition, melatonin counteracts rapid ageing, stress and cholesterol.


Where and how is melatonin produced?
In humans, melatonin is produced in the pineal gland of the brain, based on the signal substance serotonin. Serotonin contributes to the regulation of sleep, mood, appetite and memory.

The body's content of serotonin increases at dusk, and the beginning of secretion of melatonin initiates the sleep rhythm. If you have too little serotonin in your body in the evening, it affects the production of melatonin and thus the quality of sleep.

It is important for the production of melatonin that there is enough serotonin available in the body. This is ensured by consuming vitamin B6 and foods that contain tryptophan, which is the precursor to serotonin. These foods include: cottage cheese, brown rice, avocado, bananas, walnuts, tomatoes, soy proteins and turkey.

In addition, the amount of melatonin is largely determined by the brightness of the surroundings. The darker the environment, the more melatonin is produced.

The brightness (day/night) is picked up by photoreceptors in the retina of the eye, which send a message to the body's internal clock - a small group of nerve cells in the brain. The internal clock registers the brightness over time and can thus control the circadian rhythm, and the production of melatonin in the pineal gland.

The production of melatonin is at its peak in 5-10 year olds and then decreases with age.

When is melatonin produced?
The production of melatonin is promoted in darkness and inhibited in light. This is why this hormone is also called the hormone of darkness.

A natural production of melatonin therefore takes place in the evening and especially at night, when the eyes are naturally subjected to darkness - and thus are not exposed to either daylight or artificial lighting.

The use of artificial lighting in the evening and at night decreases the duration of melatonin production. This brings disorder to many of the body's functions and is considered by researchers to be the cause of the increasing incidence of sleep problems, but also breast cancer and other forms of cancer in industrialised countries.

What light affects the production of melatonin?

In our modern world, we are exposed to light pollution in the evening and at night, which comes from indoor and outdoor lighting, computers, TV, tablets and smartphones. This light pollution is characterised by the emission of blue light and creates an imbalance in our natural circadian rhythm by inhibiting the natural production of melatonin. It is the blue light in the light spectrum (446-477 nanometers) that inhibits the production of melatonin.

How long does the body produce melatonin?
Over a 24-hour period, the body can maintain a maximum production of melatonin for 12 consecutive hours at most. Normally, the daily maximum production of melatonin in adults lasts 9-10 hours in a row.

However, there will always be an insignificant minimal production of melatonin, regardless of light conditions.

Melatonin and sleep
The need for sleep can vary greatly from person to person and depends, among other things, on melatonin production. Children and young people need many hours of sleep per day (10-15 hours), while adults and older people can manage with far fewer hours of sleep per day (5-10 hours).

It is therefore important to ensure that the eyes are not exposed to blue light for the recommended 8-10 hours per day, when the body produces the melatonin needed to ensure good sleep in addition to disease-fighting body functions.

If you do not have the opportunity to sleep for 8-10 hours per day, there are simple and side-effect-free methods, such as the use of sleep glasses, to ensure melatonin production anyway, without changing lifestyle.

Melatonin and sleep glasses
The production om melatonin can be ensured by sleep glasses, which block blue light of up to 530 nanometers in the light spectrum.

You can easily watch TV, work with the computer and read with sleep glasses on. You can maintain virtually all your normal activities after dark - and at the same time ensure a healthy and natural production of melatonin.

It is also possible to use special light sources that filter out the blue light, and to mount screen filters directly on the PC and TV and achieve the same effect.

Research regarding melatonin and light

Below are a number of summaries/abstracts of scientific trials dealing with melatonin and light. The abstracts originate from medical records (copyright).