exposing yourself to daylight helps reduce age-related sleep disorders, according to a study

The frequency of sleep disorders increases with aging. Favoring daylight seems beneficial to avoid them or reduce their impact.

A new study by an Inserm team, published Tuesday January 30, shows that to reduce age-related sleep disorders, one of the solutions is to expose yourself more to daylight.

It has long been known that light is essential for regulating sleep since it influences the production of melatonin. The sleep-inducing hormone is produced in darkness. But with aging, melatonin production becomes less and less effective. This team of Inserm researchers from the Lyon neuroscience research center therefore wanted to know if the aging of the lens of the eye could explain changes in sensitivity to light and the increase in sleep disorders with age.

These scientists carried out tests on a group of volunteers. On one side, 25-year-olds, and on the other, 60-year-old volunteers, all were exposed to nine lights of different wavelengths and colors in the middle of the night, when the body releases more melatonin. Result: the photoreceptors of the lens of the eye, the cells which activate to influence the secretion of melatonin, are not the same in young people and in older people. This difference influences the secretion of melatonin, the sleep hormone.

Concrete implications

This work shows that older people have a greater need to be exposed to lights with the same wavelengths as daylight, the researchers explain. We should therefore adapt light therapy advice according to age. This relatively little-explored avenue so far could be a good alternative to medication for some. According to figures from the High Authority for Health, a third of those over 65 regularly consume sleeping pills. And when we talk about adjusting to daylight, it’s important to go out, and not just open your curtains or shutters.

To take effect, the light must have a fairly strong intensity, more than 2,500 lux, but the lighting in a room is generally 10 times less strong. On the other hand, outside, even on overcast days, the natural light is intense enough to influence our internal clock. When we expose ourselves to this sunlight during the day, especially in the morning or early afternoon, we fall asleep more easily in the evening and we also wake up early, and more easily, the following night. An observation valid at all ages, but even more so as we get older.