It's 5 a.m. and you've spent the past hour staring at the ceiling.

You climbed into bed around 1 a.m. and fell asleep almost immediately. Then, suddenly it's 2 a.m. and you're wide awake. Your pulse is racing, head thumping.

You try to calmly assess the situation. You tell myself to relax and even manage a laugh as you recall a sensitive friend's advice: "Insomnia? Go to sleep and forget about it."

You close your eyes, take deep breaths, and within 40 minutes or so, you're skimming the surface of sleep's enticing depths once more -- never entirely there, but it sure beats the ceiling.

At 4 a.m. You're back to the ceiling, only this time you know there's no return. This is the most agonizing time, an insomniac's nightmare. In a few more hours the alarm will ring. You'll get out of bed, foggy-headed and puffy-eyed, and start to add up the damage (one hour between 1 a.m. and 2 a.m., another between 3 and 4 . . .). You already know, some four hours before you've even left for work, that this is going to be a very long day.

For those who sleep like a log, sleeplessness may seem inconceivable. After all, anyone can do it, right? Pull back the covers, lie down, close your eyes . . .

Yet, for an estimated one in every five people worldwide, the land of nod is as distant as nirvana.

In recent years, fatigue and sleep disorders have become a social norm. And while poor sleep is not injurious in itself, the indirect consequences are an eye-opener. Experts agree that not only is insomnia a social and economic burden, it is also costing lives.

According to the National Sleep Foundation's 2000 Sleep in America poll, one in four Americans suffer from chronic lack of sleep. Similar figures have been reported in Britain and Canada. Japan is faring a little better: The National Institute of Mental Health reports that around 22 percent of Japanese adults suffer from insomnia.

Insomnia is variously defined as difficulty in sleeping or insufficient sleep. Experts generally agree that "sufficient" sleep for adults is around eight hours a day, but with individual sleep requirements varying widely, it is often interpreted as enough sleep to guarantee mental alertness during the day.

An NIMH study published in January reports that about 65 percent of the Japanese population sleep less than seven hours a night. The figure is less than half that in the United States. The problem, it seems, will not be put to bed overnight.

Many people will have experienced insomnia at some time in their life. Transient insomnia, for instance, is brought on by a temporary change in the sleep-wake cycle, jet lag being the most common example.

Chronic insomnia is much more complex, often resulting from a number of underlying conditions, including physical or psychological disorders such as asthma or depression. It can also be caused by lifestyle irregularities, such as abuse of caffeine or alcohol, or lengthy afternoon napping. It can last for months, sometimes years.

According to Hiroshi Ito of Jikkei University School of Medicine, it's a myth that if you can't sleep you'll eventually die or go insane. But the effects of sleep deprivation can be fatal, even if not directly so. "Sleep disorders are not dangerous illnesses -- directly. Indirectly, . . . [they] are the cause of major social problems," said Ito, whose book "Sleep Disorders" was published earlier this year.

A common side effect of insomnia is daytime sleepiness, which in turn can cause a variety of accidents and decreased productivity at the workplace, he explained.

The modern malaise

Experts agree that a major cause of insomnia is increased stress brought about by our 24-7 society. Round-the-clock services are now the norm, meaning employees are often expected to work longer hours, and shift-work -- often a fast-lane to sleep disorders -- has become more widespread, Ito said.

According to Makoto Uchiyama of the National Institute of Mental Health, sleep has become a luxury, not a necessity.

"Today, short sleep time is the norm in all advanced nations, but it is important to note that it is much easier for people suffering from excessive stress . . . to become insomniacs," said Uchiyama, who is also director of the Japan Society of Sleep Research.

In 1999, Uchiyama headed the nation's first epidemiological study of insomnia among Japanese. The study found that there is greater possibility of insomnia among the unemployed, those who do not habitually exercise, those who perceive their health status to be low or those who suffer from stress.

One major difference between Japan and other developed nations is that, of the Japanese who admitted to getting less than seven hours sleep a night, less than 20 percent thought their sleep time was insufficient, Uchiyama explained.

Wake-up call

Insomnia is a symptom, not an illness, but the causes are often difficult to isolate and the cures are fuzzy.

A frequent cause of midsleep awakenings are neurological disorders, such as sleep apnea (obstructed breathing during sleep) or restless legs syndrome, but if those symptoms are ruled out, sufferers should take a hard look at their lifestyles.

Identifying behaviors that may aggravate insomnia, such as excessive intake of caffeine, alcohol and nicotine before bed, and controlling them can make a difference. Exercise is also advised, though not late in the evening.

Many people attempt to overcome insomnia by going to bed earlier, which can be counterproductive, experts say. In fact, most recommend a reduction in the amount of time in bed. For example, someone who spends eight hours in bed and wakes up four times for 15 minutes should reduce his/her time in bed to seven hours.

"[Optimum] length of sleep is determined by the sleep center of the brain. We cannot control the sleep center by our own will . . . and we can't decide the length of time we sleep simply by the length of time we want to sleep," Uchiyama said.

We are able, however, to ensure we get a good night's rest by observing good sleep hygiene, which includes associating the bed with sleep rather than studying or watching television, and keeping a regular day-night cycle.

Get with the rhythm

Awakening and going to bed at more or less the same times every day ensures our body, or "circadian," clock will tick along nicely.

Our body clock is set into motion by morning sunlight. Around 14 hours after first exposing ourselves to daylight, the hormone melatonin is secreted from the brain and triggers our first wave of sleepiness. Within a couple of hours, the effect of the melatonin peaks, and it is then that we should hit the sack.

But, we're only human. There's coffee, alcohol and that late-night movie all waiting to disrupt the balance, Uchiyama explained.

"We can stay awake by our own volition, but we can't will ourselves to go to sleep because the time we are able to fall asleep naturally is predetermined by those first rays of sun."

Those who think they can catch up on lost sleep by lingering longer between the sheets on weekends are in for a nasty surprise come Monday morning, Uchiyama stated.

"Oversleeping can result in postsleep inertia. It messes up the body clock, resulting in a heavy head and Monday blues," Uchiyama said, adding that the result is basically the same as jet lag.

An effective way to counter this is to wake up, if only briefly, on weekends at your regular weekday time, or take naps in the afternoon, according to Ito. "Naps are effective providing they do not exceed an hour's duration," he said.

While identifying physiological or behavioral factors can help insomniacs who find it difficult to maintain sleep, those who find it difficult to initiate sleep often suffer more psychological problems, such as anxiety or depression. People who are concerned about the possible harmful side effects of sedatives might want to consider natural therapies, such as acupuncture, aromatherapy and reflexology.

Nobuyuki Takeuchi, president of Akahigedo, an Eastern medicine clinic in Tokyo, said insomnia is the result of "heat" retained in the internal organs, particularly the liver. Releasing that heat via a mixture of acupuncture and Chinese medicine will put an end to an insomniac's nightmare within a month, he said.

Meanwhile, Charlie Badenhop, a Tokyo-based hypnotherapist from the U.S., said hypnotherapy bridges a gap between doctors and academics in the field of psychology "who are excellent at describing causes of sleep disorders but do not have great skills in actually finding a solution."

Placing clients under hypnosis, he said, can promote relaxation and help free the mind to identify the cause of sleeplessness.

"Insomnia is basically a message from the body or unconscious mind that something you are not attending to needs to be attended to," Badenhop said. "[Hypnotherapy] is a method to investigate what that message is -- for example, fear, stress, trouble at work -- and can help people realize the way to deal with it."

So before you arrive once again on the ceiling at 5 a.m., searching for those lost sheep, do yourself a favor and read our tips on how to slumber. You might find your ticket to the land of nod.