People sleep in order to function in a healthy and normal way. Sleep is a dynamic process during which the brain is very active. Millions of people in the United States are suffering from chronic long-term sleep disorders each year. This does not include yet those other millions of people who are suffering from occasional sleep problems.

There are more than 70 different sleep disorders that are generally classified into one of three categories:

?lack of sleep ? insomnia

?disturbed sleep ? obstructive sleep

?excessive sleep ? narcolepsy

Sleep disorders, when properly diagnosed, can be easily managed. The most common sleep disorder is insomnia which occurs more often in women and in the elderly. People with sleep disorders can take over-the-counter sleep aid drugs, which are most effective for an occasional sleepless night.

Age is a significant factor in determining the amount of sleep that a person needs to function normally. Infants, for instance, sleep most of the day for about 16 hours while teenagers usually need about 9 hours a day. Adults need an average of 7 to 8 hours of sleep a day. However, the elderly usually have shorter periods of sleep and spend less time in deep stages of sleep. About 50% of adults over the age of 65 have some type of sleep disorder, although it is not clear whether this is a normal part of aging or a result of medications that older people commonly use.

The ability to sleep and to wake up are influenced by various chemical changes in the brain and in the blood. There are certain foods and medicines that alter the balance of these chemicals which also affect how well we sleep. Examples of these are caffeine which can cause insomnia, and antidepressants which can cause a loss of REM or Rapid Eye Movement in sleep. Also, smoking and alcohol can greatly contribute in a loss of deep sleep. Both REM and deep sleep are essential parts of the normal sleep cycle.

Avoid mixing alcohol and sleep aid drugs. Alcohol can increase the sedative effects of the pills even in small amount, causing dizziness, confusion, or fainting. Alcohol in itself can already cause insomnia.

There are five stages of sleep cycle that repeats over and over during a single night's rest: stages 1, 2, 3, 4 and REM (rapid eye movement). Stages 1 through 4 are also known as non-rapid eye movement sleep (NREM). About 50% of sleep time is spent in stage 2 and about 20% is spent in REM which is normally more than 2 hours a night in adults. A complete sleep cycle, from the beginning of stage 1 to the end of REM, usually takes about an hour and a half.

During stage 1, the muscles begin to relax and a person can still be easily awakened. This is called light sleep. In stage 2, the brain activity slows down and eye movement stops. Deep sleep comes in stages 3 and 4, during which all eye and muscle movement ceases. During deep sleep, it can be hard to wake a person. Stage 3 is characterized by very slow brain waves (delta waves), interspersed with small, quick waves. In stage 4, the brain waves are all delta waves.

Sleep-walking and bed-wetting among children are experienced during deep sleep. On the other hand, dreams occur during REM sleep when the muscles of the body stiffen, the eyes move, the heart rate increases, breathing becomes more rapid and irregular, and the blood pressure rises.

Sleep inadequacy can have severe detrimental effects on health. Studies have shown that sleep is essential for normal immune system function and for healthy cell growth. Sleep also is essential for normal nervous system function and the ability to function both physically and mentally. In addition, sleep is also necessary to promote a relax attitude. A person who always gets enough and complete sleep is generally more focused and ready to learn.

When you are having a hard time getting a good night's sleep, prescription or over-the-counter sleep aid drugs may be an option. Be sure to use them safely and with advice from your physician. If your doctor suspects a sleep problem, he or she will look at your overall health and sleep habits.