11/20/2010 11:58 am ET | Updated Nov 17, 2011

Underground and Out of Sight: How Does a Lack of Light Affect Your Sleep Cycle?

It was amazing to see it happen -- watching the rescue of the Chilean miners one by one. And how great to have a news story that captivated our attention because of the happy ending!

Imagine being underground for 69 days. I saw that the miners were wearing special glasses provided for them by Oakley when they reached the surface, as they were not accustomed to the sunlight. From a sleep perspective, I wondered what it would be like to live in an environment with

Natural light helps reset our

We have seen something a little like this before, in the military. Living in a submarine, you may not see daylight for weeks, sometimes months at a time, and there can be some serious consequences. Granted on a submarine there is plenty of light when needed. But the miners' conditions provided almost no exposure to light for an extended time. We know that long-term disruption of a mammal's circadian rhythm has been linked to symptoms of depression, insomnia, headaches and hallucinations. And that is just a short list of the effects.

Could any serious damage have been done to the miners' sleep cycles while in the mine? It is doubtful. Once they were able to get back "on top" the necessary photons would work their magic and over time re-set the biological clocks of the rescued miners. How long will it take? It could vary but with proper light exposure probably no more than a week.

It's pretty amazing to know that we all have that reset button available. I often talk about darkness as part of my recommendations for getting a good night's sleep. But we need to remember that light is important to maintaining good

Sweet dreams,

Michael J. Breus, Ph.D.

The Sleep Doctor™