Sleep, light and health

Philip J. Goscienski, M.D.

January 2006

Can you imagine life without artificial light? In a world of lasers and lightsticks, lamps that turn on or off at the snap of finger, a clap of hands or a voice command, it's hard to imagine what it must have been like when there was no illumination except what nature provided.

Picture yourself in the Stone Age on a moonless, cloudy night when even starlight was not visible. Moving a few feet from the campfire's dying embers leaves you in total darkness until the first light of dawn. There is nothing to do except to join other members of your band, who provide comfort, warmth and security. This is how humans existed until the discovery of crude torches and later, oil lamps.

Over tens of thousands of generations many of our bodily functions have become synchronized with the day-night pattern of light and darkness. This is known as circadian rhythm and it varies with the seasons. That is, until very recently. When gaslamps replaced candles and were in turn replaced by incandescent and fluorescent lighting, artificial light allowed us to live differently than we had for millions of years. This came with a price.

Physicians have long known that heart disease is more common among night shift workers. Perhaps this is because of increased stress and chronic sleep deprivation. Certainly, there are other factors. Persons who work at night may not have comforting family relationships, may miss meals or eat poorly and could be sleep-deprived. The finding that homocysteine, an amino acid that is associated with increased risk of coronary artery disease, is elevated in night shift workers, may be a clue to their heightened hazard.

The heart seems to have a day-night rhythm of its own and disrupting the rhythm could explain why heart attacks are more likely to occur between midnight and noon in Western countries.

Breast cancer occurs with greater frequency among women who work night shifts, but it occurs less frequently among women that are blind. Exposure to light increases levels of the female hormone, estrogen, which is a known factor in the development of breast cancer.

Night shift work even disturbs the way we respond to a meal. When we eat very late in the day, it affects our output of hormones such as insulin, thyroid hormone, cortisol from the adrenal glands and several others.

What can we do about it? After all, it's not practical to go back to a life without light even if that were possible. The first step is to recognize that some of the problems that are associated with shift work are avoidable. For instance, packing a nutritious meal from home helps to avoid the pizza delivery routine or the snack-machine. A couple of pieces of fresh fruit and a ziplock back with raw baby carrots or broccoli will bolster your antioxidant level. The phytonutrients in fruits and vegetables may offset the increased risk of both heart disease and cancer.

Make daytime sleep more restful by having a definite schedule and keep the bedroom as dark as possible. Enlist the help of family by honoring the schedule and by keeping household noise down to the lowest possible level.

Taking medication to help you sleep off-schedule is not a good idea. These drugs have numerous side effects and increase the risk of falls and other accidents.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at