Note: This story is part of series on the U.S. Army Medical Command's Performance Triad -- Sleep, Activity and Nutrition.

SEMBACH, Germany -- Not getting enough sleep? It could be doing more to you than just making you tired during the day.

Sleep deprivation not only impairs an individual's mental alertness, but can lead to physical problems as well. While people may believe sleep is important for the brain, it's also important for other systems in the body.

"Most studies have been done on the effects of sleep deprivation show that sleep is helpful in restoring mood and emotion," said Lt. Col. (Dr.) Sean Dooley, medical director for the Landstuhl Regional Medical Center's Sleep Disorders Center, the only military clinic of its kind in Europe. "There's a growth hormone surge while you sleep that aids in the restoration of the brain's neurons. It's also a designated resting state for the kidneys and (gastrointestinal) tract.

"There are a lot of things happening when the brain is resting," Dooley continued. "The cardiovascular system takes a break during the resting state. It recharges your batteries. Most people think that during sleep the brain is resting but it's important for the rest of the body, too."

There are two drives in people that determine when they feel tired, Dooley said. The first is the circadian drive, in most people who work during the day, that makes most people want to sleep around 9 to 11 p.m. and wake up between 5 and 7 a.m. The circadian drive is affected by light and also leads people to have peak sleepiness periods in the early morning and right after lunch, with peak wakefulness periods in the late morning and later in the evening.

The tired feeling people get the longer they stay awake is from the homeostatic drive. Both drives usually coincide at night around the time most people feel the need to head for bed.

Most studies of sleep duration show that the majority of people need seven to eight hours of sleep to operate at their peak performance, Dooley said, although a small percentage of people can function with less or need more sleep each night. While such people do exist, it's pretty uncommon to find them.

"In the military we develop compensatory mechanisms," Dooley said. "In fact, if you only get 6 hours of sleep a night for two weeks you can be as tired as if you didn't sleep for two nights at all."

Insufficient sleep can be perceived as irritability, excessive daytime sleepiness, or problems with concentration or memory, Dooley said, but some studies have pointed to other problems that can be related as well.
"We believe it can contribute to high blood pressure and glucose intolerance as well," Dooley said. "Sleep does do something important for us besides make us feel better."

The most common complaint Dooley hears in his clinic is chronic insufficient sleep, but people can help themselves sleep better simply by preparing their bedrooms for sleep.

"You can promote healthy sleep habits," Dooley explained, saying activities can help contribute to keeping you awake longer than you'd like. "Take things like your TV, books and IPads out of the bedroom. You should avoid fatty foods and exercise right before bed time. Try a regimen of having a certain bed time and a certain rise time. You can also go into a dark room for a short period and then go back into the bedroom for sleep."

Dooley said most insomnia, or the inability to obtain adequate sleep, is behavioral in nature and can be caused by things like post-traumatic stress, anxiety or depression, and the resulting sleep deprivation can only make the daytime problems worse. Insomnia can also be learned -- when things like bereavements or the high operations tempo during a deployment are on your mind, for example.
But almost everyone, he said, has experienced adjustment or acute insomnia at some time.

"When you have a deadline coming up, or you have a formation early in the morning, you lay in bed frustrated and not able to sleep," Dooley said. "Over weeks or months behaviors form that reinforce the problem -- since you can't sleep you get up at night to clean the house or pay bills."

While there is a peak sleepiness period in the afternoon after lunch, Dooley recommends that people who are having problems sleeping at night try to resist it. Sleeping too long in the afternoon could lead to sleep problems at night, so it's best for those people to try and consolidate their sleep at night.

If somebody is having problems sleeping, they should first talk with their primary care manager since there are usually options available to them at their local military treatment facility, including sleep hygiene classes through either primary care or behavioral health that can help people learn how to better prepare themselves for a good night's sleep.

Sleep is one part of the U.S. Army Medicine's Performance Triad, which also includes Activity and Nutrition. The goal is to illustrate to patients that they can positively impact their health by investing in these triad of factors. Getting back to the basics of Sleep, Activity, and Nutrition are key in optimizing health, performance and resilience.