Another sleepless night. You toss and turn, trying to banish worries about your family, job, money. As you fret about how miserable and inefficient you'll be tomorrow, you become even more tense. Sometimes, even with your mind seemingly clear and relaxed, sleep just doesn't come.

An estimated 40 percent of adults in the United States suffer from sleep disturbances each year, and 60% of those report having insomnia a few nights a week or more.

Insomnia includes having trouble falling asleep, having trouble getting back to sleep, and waking up too early. It's more common in people with a history of depression and bipolar disorder.

Sleep maintains your circadian rhythms (the 24-hour cycle that regulates your physical and mental functions. It's been found that a good night's sleep helps the brain commit information to memory. Many adults function best with around eight hours of sleep, but each person has unique needs.

Our brain makes mood-enhancing hormones while we're sleeping, and if we get too little sleep, it won't make and store enough for the next day. A lack of sleep leads to poor concentration, irritability, anxiety, depression and low energy. And, chronic sleep deprivation can cause weight gain by affecting the way our bodies process and store carbohydrates and by altering levels of hormones that affect our appetite.

More than 80 percent of individuals who suffer from depression also have sleep abnormalities, and if sleep problems persist after depression has subsided, the risk of relapse and even suicide increases. Research has found, and many of us know from experience, that sleep problems can lead to depression, and depression can lead to sleep problems. And, lack of sleep can trigger mania or hypomania in people with bipolar disorder. A regular sleep-wake schedule can help prevent occurrences.

What causes insomnia?
In addition to depression symptoms, stressful events can cause insomnia and so does eating too close to bedtime. Alcohol can cause you to fall asleep but cause a rebound effect two or three hours later and keep you awake. Some medications can cause sleep disturbances, including many of those for mood disorders.

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Tips for a good night's sleep >>

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Sources
Ronald R Fieve Bipolar II
Ellen Frank, Ph.D., professor of psychiatry and psychology at the University of Pittsburgh Medical Center's Western Psychiatric Institute and Clinic (WPIC) and co-author of one of the studies
National Sleep Foundation
National Institutes of Health
Patel, Sanjay R. 1; Malhotra, Atul 2,3; White, David P. 2,3; Gottlieb, Daniel J. 4; Hu, Frank B. 3,5,6 (2006) Association between Reduced Sleep and Weight Gain in Women, .American Journal of Epidemiology, 164:10

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