Sleep disorders are any difficulties related to sleeping. They may include difficulty falling or staying asleep, falling asleep at inappropriate times, sleeping excessively or abnormal behaviors during sleep.

More than 70 million Americans have a sleep disorder, according to the National Institutes of Health. Among those, almost 60 percent have a chronic disorder. Sleep disorders affect people of all ages, especially infants and elders.

More than 100 sleep disorders have been identified, including insomnia, sleep apnea, narcolepsy, restless legs syndrome, night terrors and sleepwalking.

Sleep disorders may be caused by a variety of factors. Medical conditions (e.g., asthma) or the use of certain medications may affect sleep. Lifestyle factors, such as working the night shift, may also contribute.

Signs and symptoms of sleep disorders may include difficulty falling asleep, waking up during the night and excessive daytime drowsiness.

Sleep disorders may take time to diagnose. If the cause of the sleep problem is not apparent, patients may be referred to a sleep center where sleep patterns are analyzed.

Treatment of sleep disorders varies depending on the cause of the disorder. Treatment may include lifestyle changes (such as avoiding caffeine and alcohol), losing weight, exercising and medications. Patients may also receive relaxation therapy or cognitive behavioral therapy (CBT). Left untreated, some sleep disorders can be life-threatening. Excessive daytime sleepiness can cause people to fall asleep at inappropriate times, such as while driving.