At night, you can’t sleep in complete darkness? Do you need a little light to get to sleep? Be careful: according to a new study from the University of Leiden (in the Netherlands), this habit could be really bad for your health.
“In humans as in mice, the natural light / dark cycle must be preserved” explains Johanna Meijer, main author of this work published in the specialized journal Current Biology. “We have found that when this biological rhythm is disrupted, the health consequences are significant.”
The researchers carried out an experiment on a group of mice: for 24 weeks, they were continuously exposed to a source of artificial light. Result: at the end of the experiment, they observed disturbances in the area of the brain which corresponds to the circadian rhythm (the suprachiasmatic nucleus, seat of the famous “biological clock“).
Muscle and bone disorders
This disturbance had very concrete consequences: after 24 weeks, the mice exhibited abnormal muscle weakness and their bone density (measured by bone densitometry) was also less important than average. “We also observed negative effects on the immune system, but further studies will be needed to verify this point.”
Good news: the effects are reversible. “When we restored the natural light / dark alternation, these health concerns disappeared after two weeks” explain the researchers. They estimate that 75% of the world’s population is exposed to artificial light at night.
We already knew the ravages of artificial light: decreased fertility, sleeping troubles, overweight, dermatological problems … What if we learned to sleep in complete darkness, to protect our health?