Close shutters, blinds or curtains, then turn off all light sources before going to sleep and you will reduce the risk of cardiovascular disease and diabetes. From Northwestern University researchers (United States) has in fact just demonstrated that exposure to ambient lighting, even moderate, during the hours of sleep, increases insulin resistance and harms good cardiovascular functioning.
Previous studies had shown that exposure to light during the day increases alertness and heart rate, via activation of the sympathetic nervous system. “The study results indicate that there is a similar effect when light exposure occurs during nighttime sleep,” said Dr. Phyllis Zee, lead author of the study published in the journal PNAS. “The heart rate increases and the organism cannot rest and restore its functions properly”.
Eliminate all sources of light
Exposure to a source of artificial light during the night is more common than you might think: a large proportion of people fall asleep with a bedside lamp on, in front of the television set, or in a room bathed in light from a street lamp.
The study participants’ brains reacted like those of someone with light, fragmented sleep. The researchers also discovered that in the early morning, our pancreas produces more insulin when we have slept in a room with too much light. “Previous work had shown that people exposed to light during their sleep were more overweight or obese. We show why this happens and what is the mechanism at the origin of overweight” continues the doctor who gives his advice for better to sleep :
- If you need a night light (to avoid falls when traveling at night, for example), place it at ground level to focus on the light source.
- Red or amber light is kinder to the brain. Do not use white or blue light.
- If there is an outside light source, use an eye mask, such as on an airplane, or blackout curtains. And move your bed so the light source doesn’t fall on your face.
Source : Light exposure during sleep impairs cardiometabolic function, PNAS, March 2022
Read also :
- What is this surprising capacity that our brain has when we are asleep?
- Sleep positions: what they say about you
- 12 things not to do before bed to sleep well
