Sleep in dark

Our biology asks natural sleep in dark but due to demanding work and lack of schedule, many people end up sleeping with lights on while working on computers or watching television. In this article we will discuss the importance of sleeping in dark in terms of medical point of view.

We might be aware of circadian rhythm(our biological clocks) which is a roughly 24 hour cycle in the physiological processes of living beings, including plants, animals, fungi and cyanobacteria.

A key factor in regulating circadian rhythms thus also our sleep is exposure to light or to darkness. As exposure to light stimulates a nerve pathway from the eye to parts of the brain that control hormones, body temperature and other functions that makes us feel sleepy or awake.

Excess light, just before bedtime may prevent from getting a good night’s sleep. According to EurekAlert, a recent study at Ohio State University looked at mice housed in a lighted room for 24 hours a day and mice housed in a room with a normal light-dark cycle. The study found that mice exposed to 24-hour light exhibited more symptoms of depression than the other mice.

The following point may be considered for maintaining healthy exposure of light:

  • During the day, maintain natural bright indoors or use artificial light sources. Take some time to find sunlight.
  • At night, Sleep in dark. Eye mask or light blocking curtains could be used for limiting external light. A low light night lamp could be used particularly if one has habit of waking up in middle of night for toilet etc.
  • Limit dozing with the television or computers or lights-on right before sleep.
  • A good sleep schedule is particularly important for infants and children, as it directly impacts mental and physical development. For a baby circadian rhythms develop at about six weeks, and by three to six months, most infants have a regular sleep-wake cycle.

References and Further studies:

  1. Sleep foundation organization (
  2. Eurekalert! (