Keep It Dark To Sleep Better

January 25, 2011 by  
Filed under Health

Many things can affect our quality of sleep, and the links between poor sleep and health are well established. A new study shows that just turning out the light when you go sleep is not enough and can increase your risk of both high blood pressure and diabetes.

This comes from a recent study in The Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM) which reveals that exposure to electrical light between dusk and bedtime strongly suppresses melatonin levels. Why is this important? Because your body relies on processes regulated by melatonin signaling, such as sleepiness, body temperature, blood pressure and glucose homeostasis.

Our bodies produce this hormone at night via the pineal gland in the brain and because today we are now routinely exposed to electrical lighting at night the study wanted to establish whether exposure to room light in the late evening may inhibit melatonin production.

The study was carried out by Harvard Medical School in Boston, Mass and involved 116 healthy volunteers aged 18-30 years who were exposed to room light or dim light in the eight hours preceding bedtime for five consecutive days. What they found was that exposure to indoor light has a strong suppressive effect on melatonin production;
exposure to room light before bedtime shortened melatonin duration by about 90 minutes when compared to dim light exposure and exposure to room light during the usual hours of sleep suppressed melatonin by more than 50 percent.

Suppression of melatonin through light exposure has been hypothesized to increase relative risk for some types of cancer and melatonin receptor genes have been linked to type 2 diabetes. This is obviously an important factor for shift workers who are exposed to indoor light at night over the course of many years, but also for anyone who happily sits up in bed reading for an hour so before going to sleep.

Daylight and darkness are both good for our health, but the availability of constant artificial light may need to be monitored. If you can’t reduce the amount of artificial light you are exposed to you could at least in the few hours before bedtime make sure your lights are dimmer – not full and bright as that apparently really will make a difference – and certainly keep light in the bedroom as low as possible.