Philip J. Goscienski, M.D.
November 2009
It was only a little more than a hundred years ago that the electric light bulb made its entrance onto the human scene. Back in the Stone Age our ancestors had nothing brighter than a campfire. That was, it seems, a valuable health advantage.
Humans don't function well during the hours of darkness and it's not just because we lack the large, light-gathering eyes of the owl or bat-like sonar. We are day creatures that have evolved over thousands of generations to respond to the day-night cycle, falling asleep when the sun goes down and rising with it at dawn. Our body chemistry follows a circadian rhythm (literally: about the day) that is not compatible with our electric-powered lifestyle.
Modern lighting made humans more productive but what nearly everyone perceives as a blessing has some significant biological disadvantages. Artificial light contributes to the overall poor health of millions of Americans. Sleep deprivation and hormone disruption contribute to heart disease, cancer and diabetes. A lack of sleep puts a damper on our immune system, not exactly what we need in an age of pandemic influenza and other newly emerging infectious diseases.
Sleep, as scientists point out, is a restorative process that goes beyond renewing energy for day-to-day living. It is also a time for repairing minor injuries that happen in everyday life. An example is the damage that occurs during infrequent work or exercise and that is perceived as muscle soreness that lasts for a day or two.
Certain immune cells increase during sleep and sleep deprivation reduces the effectiveness of the immune system. In volunteer studies, persons with less than 7 hours of sleep were nearly 3 times as susceptible to a cold virus as those who slept 8 hours or more.
The human immune system is ancient in evolutionary terms and it has been functioning in a night-and-day rhythm for millions of years. It doesn't just protect us from germs. Disruption of the circadian rhythm adversely affects the hormonal and immune systems that keep cells from going out of control to produce cancer. The incidence of breast cancer is higher in night-shift workers and sleep disturbance might hasten the growth of tumors.
Humanity as a whole will never return to the sleep pattern of the Stone Age but it makes sense to get adequate sleep and burn less of the midnight oil.
Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.