Wide awake? Insomnia may or may not be stress-related.

Now I lay me down to sleep ..." begins the children's prayer. Although tonight will find most of us resting comfortably in our beds, some 30 million adults in America will toss and turn for hours, seeking that elusive "good night's sleep."

All of us have experienced temporary insomnia, but for some it's a serious problem. Since the development of sleep disorders centers (usually associated with universities or medical centers), researchers have gained insights into the causes and treatments of insomnia.

What is insomnia? The word insomnia simply means sleeplessness, but insomnia generally refers to a person who has difficulty falling or staying asleep. Since sleep disorders are found under many categories and stem from varying causes, researchers have developed a new term that more accurately describes the condition: DIMS, or disorders of initiating and maintaining sleep.

There are three basic types of insomnia: transient, which lasts a few nights and is generally associated with some type of physical or emotional stress; short-term, which may last several days or weeks; and chronic, which may go on for years. Insomnia is considered serious when it begins to affect daytime behavior and performance. Those who experience transient insomnia rarely seek professional help, but short-term and chronic sufferers may actually prolong their condition by worrying about the insomnia and trying to treat it themselves.

Causes. Insomnia is a symptom, not a disease, and is usually caused by a combination of factors. Researchers have found at least four groups of factors that can be underlying causes of insomnia: physical and psychological predisposition; the use of drugs and alcohol; disturbing environments and bad habits; and negative conditioning. Overcoming insomnia depends upon recognition of these factors and initiation of appropriate treatment.

If you are physically predisposed to insomnia, your brain may have a hyperactive arousal system, much like a sensitive burglar alarm. You would probably have a faster heartbeat and higher body temperature than a sound sleeper. You may be awakened by leg jerking, and the slightest noise can bring on a surge of adrenaline, further contributing to sleeplessness.

Psychological predisposition is debatable, but many researchers contend that the personality traits of certain individuals contribute to insomnia. This includes people who are highstrung and who react more negatively to disappointments and problems. They usually spend a great deal of time thinking about sleep, and may even work themselves into a panic over their insomnia.

Drugs: More harm than good. Approximately 10 million Americans will use drugs to combat insomnia this year. Contrary to popular belief, sleeping pills and alcohol can actually disrupt sleep by inducing a shorter, more disturbed sleeping pattern typified by abnormal REM (rapid-eye movement) sleep periods. They also inhibit production of dopamine, a neurotransmitter in the brain that promotes sleep. This "rebound insomnia" often leads to addictive behaviors because the sufferer takes more drugs or alcohol, thinking it will bring relief.

While some tranquilizers and sleep-inducing drugs can be beneficial for transient or short-term insomnia, they should be prescribed by a physician after a thorough exam. Sleep experts discourage the use of drugs for more than a few weeks.

The traditional warm glass of milk has received some attention from researchers because it contains L-tryptophan, an amino acid that occurs naturally in foods. Although it has not been scientifically proven effective, tryptophan does seem to help some people with mild insomnia. However, the safety of using it in supplement form has been questioned because of a link with a serious blood disorder. It's probably best to let your body regulate its own blood levels of tryptophan by eating foods high in carbohydrates (such as cereal or crackers) along with a glass of milk before bedtime. Avoid sugar--your body will secrete insulin to metabolize the sugar, and excess insulin can cause restlessness and anxiety. And of course, avoid caffeine.

Look at your environment and lifestyle. Noise, light, heat, and cold can affect your ability to sleep. Exercising too close to bedtime can keep you up. Relaxing too much during the day can disrupt your "circadian rhythm," as will frequent napping. Even sleeping late on a weekend day can cause insomnia the next evening and may contribute to that hangover feeling on Monday.

Changing your sleep environment can be as easy as buying earplugs or hanging dark curtains. If you take a little time to discover what annoys you when you're trying to go to sleep, you can often correct the problem.

Train yourself to establish good habits--having a consistent bedtime and rising at the same time every morning can help regulate your biological clock. A walk after dinner can work some of the tension out of your muscles, and a light snack before bed can cause drowsiness by directing more blood flow to the stomach and away from the brain.

Negative conditioning can become a vicious cycle. You may begin to dread going to bed because you're afraid you won't be able to sleep, and you know if you don't sleep, you won't be able to work, etc. Your bedroom may become the symbol of your ongoing battle with insomnia, and everything associated with bedtime will take on a negative connotation. Sleep disorder centers help people break that cycle with sleep restriction therapy. This focuses on improving the quality of sleep by restricting the time spent in bed. The therapy is highly effective when a person is motivated enough to stick with it.

There are approximately 100 sleep disorder centers in the United States. These centers are usually staffed by doctors specializing in neurology, pulmonary medicine, and psychiatry. They work together to determine the source of your insomnia and prescribe appropriate treatment.

The centers also determine if you have an underlying medical condition that is contributing to the insomnia, or if you are taking medication that is disrupting your sleep.

Our needs for sleep vary according to age, health, and stress. But if you suffer from more than an occasional bad night, you might want to seek professional help. Consult your doctor, or contact a sleep disorder clinic in your area.

Jan Stone writes from Rogersville, Missouri.

To Improve Your Sleep

Here's what the experts say:

* Exercise regularly--but not within three hours of bedtime, or you'll raise your body temperature and adrenaline levels.

* Give your mind an hour or so to wind down before bedtime. Balancing the checkbook, reading work-related documents, or doing other mentally taxing activities won't ease you into sleep. Listening to soft music is a better idea.

* Eating heavy food or drinking too many fluids too close to bedtime is an invitation to insomnia, as is consuming caffeine. Alcohol has a rebound effect that can lead to fragmented sleep later in the night.

* Create a bedroom environment conducive to sleep. Find ways to eliminate intrusive noises, keep out light, and don't overheat your room.

* Hide your bedroom clock once you have set the alarm. It's hard to relax when you awake at 4:00 a.m. and know your day starts in just a few hours.

* If you can't sleep, don't toss and turn. If you're awake for more than 15 minutes, turn on the light and do something else.

* Get up at approximately the same time each morning, even on weekends. Many people attribute Sunday night insomnia to anxiety about going back to work. But often it's because they've slept late the previous two mornings and their body clocks are out of sync. Avoiding naps during the day also helps.

* Keep a journal for a week, recording how long it takes you to fail asleep, how many times you awake, and how well you feel in the morning. Also note habits--reading in bed or late-night exercise--that may foster insomnia. Then change some of those habits and record your sleep patterns again to see if they improve.