Why spend the afternoon in the sun can disrupt the sleep of teens

When a teenager finds it difficult to fall asleep, the reason may come from his exposure to the sun. Indeed, according to a new study published in the journal Biological Timing and Sleepnatural light could disrupt the sleep of young people.

Melatonin, sleep hormone

The melatoninalso called sleep hormone, facilitates falling asleep. Exposing to daylight allows our body to determine its biological clock. So, when the sun drops, the concentration of melatonin in the blood increases so that we want to sleep.

But this natural cycle can be disturbed by the artificial light of the evening, especially that of the screens, which delays the secretion of melatonin and keeps us awake. During their work, scientists therefore wanted to understand whether the exposure to natural light at the end of the afternoon and in the early evening could reduce the negative effects of that artificial.

They have specifically worked on adolescents because they often lack sleep and use a lot of screens. Their goal was to study the impact of the exposure to a moderate or strong natural light at the end of the afternoon and at the start of the evening on their sleep.

For this, they tested different lighting out of 22 teenagers aged 14 to 17. For three 18.5 hours sessions each, the participants were exposed to three light intensities: weak, moderate or bright. Before and after, adolescents had to give a few drops of saliva. These samples were used to assess their melatonin levels. In addition, scientists measured other indicators such as skin temperature or drowsiness.

Strong light reduces melatonin levels

Results: exposure to strong light at the end of the afternoon and early evening reduces melatonin levels and delays the secretion of this hormone of about 21 minutes. Adolescents therefore find it difficult to fall asleep. On the other hand, the impact of low and moderate lights was either nonexistent or not significant.

The sleep of adolescents can therefore be impacted by the natural light of the very end of the day. Exposing yourself after school is therefore not a good option to compensate for the harmful effects of screens and other artificial lighting of the evening. When the sun is strong, it can disturb sleep until three hours after the exhibition.

Between 12 and 18 years old, young people lack an average of one to two hours of sleep per night during the school period, according to theHealth insurance. To remedy this, the authors call for structural changes, as to delay the start time for the lessons so that adolescents who find it difficult to fall asleep in the evening can catch up in the morning.