If you're like most people, you probably think getting an hour or two less sleep here or there is no crisis. It's worth it to get more done during the day-and possibly at night.

But you're not doing anyone a favor by sacrificing those hours of sleep. In fact, studies show that you may be putting your job, your life, and others' lives at risk.

Why? Sleep is a necessity that your body and mind demand (see "To Sleep, Perchance to Learn"). When you go without it, the sleep' debt accumulates (see "An IOU for Sleep"), and it disrupts your waking life. You find yourself dozing in class, in meetings, at the movies, even at dinner. Excessive sleepiness raises red flags in our hectic, hurry-up-and-do-more society. If you sleep all the time, you are accused of being lazy, or told to see a doctor because "something's wrong with you." And something is wrong. You are simply too tired.

The National Institute of Health (NIH) National Heart, Lung and Blood Institute advises that there are two periods when the body is most likely to feel sleepy:

1) Late at night, generally between midnight and 7 a.m.
2) Mid-afternoon when the body is digesting lunch, between 1 and 4 p.m.

If people ignore the natural inclinations of their body during these times, there is a higher risk of falling asleep unintentionally at other times when it may be inappropriate or even dangerous.

Sleepers Against Drowsy Driving

The most dangerous effects of these constant nap attacks can be seen in recent driving statistics. The National Sleep Foundation has released the results of the 2000 Sleep In America poll. According to the survey, nearly one in five drivers dozed off while driving last year. Other disturbing findings:

• 51 percent of adults-over half in America-confess that they have driven while drowsy.
• 24 percent of Generation Y (18-29 years old) drivers have fallen asleep at the wheel during the past year.
• Despite stereotypes, older people fare better and are more alert. Only 15 percent of people 30 to 64 years old are likely to nod off in traffic, and just 6 percent of drivers 65 and older nap on the road.
• Car crashes that result from drowsy driving are most common in younger people, especially 20 year olds.
• Forty-two percent of adults become stressed when they are sleepy behind the wheel, while 32 percent are impatient and make reckless decisions.
• Both younger people (22 percent) and adults (12 percent) hit the gas pedal when they are sleepy.

Driving when you know you are tired has dangerous consequences. Dateline NBC performed one experiment with drunk drivers, and one with eight sleepy drivers. Half of the sleepy drivers got no sleep the night before, and the other half deliberately shortened their sleeping time by two to three hours the week before. Dateline and Dr. William Powell of the national Sleep Disorders Research Center instructed the drivers to navigate an obstacle course of plastic cones and pop-up objects The results were dramatic: One of the all-nighter drivers, normally a truck driver, hit a pop-up dog. In the second group, the drivers kept closing their eyes and nodding off while driving. Like their sleepless counterparts, they knocked over plastic cones and pop-up objects. Interestingly, the drunk drivers and the sleepy drivers preformed similarly in the driving test.

Commentator and pundit Arianna Huffington quipped in a column on her Web site, "But while we have national campaigns against drunk driving and speeding, there is no outcry against driving while sleepy. There is no MAME (Mothers Against Motorist Exhaustion), and no public service announcements reminding us that 'Friends Don't Let Friends Drive Pooped.' "

The NIH has some simple solutions for avoiding sleep-related accidents. The basic message: Plan ahead if you're going to be in a car for more than an hour at a stretch.

• Avoid driving during the "red-eye hours" of midnight and 7 a.m.
• Consider putting off your car trip until the morning, then get a good night's sleep in the meantime.
• If you are traveling with other adults, take turns at the wheel often.
• Take frequent rest stops, especially if you are driving alone.

When you are in a car, your attention is pulled in all directions-the road, traffic, signaling, turning, the weather, trying to find a destination. Don't add one more variable by driving when you feel tired.

Too Tired To Function

Car accidents are not the only problems associated with dozing off. The costs of problem sleepiness to your everyday life and social life can mount as you:

• Struggle to stay awake even when sitting quietly reading
• Have difficulty concentrating at school, work or home
• Perform poorly at work or school
• Experience lapses in memory
• Cannot control your emotional responses and become short-tempered, impulsive or irritable with others
• Have slow responses or reactions

All of these, according to the National Institutes of Health, are signs, as well as effects, of problem sleepiness. The problem can escalate into greater costs to society, such as lost jobs and expulsion from school, lost income, and family dysfunction.

Being too sleepy is not a matter of being "lazy" but of not obeying your body and sleeping when you are supposed to. And problem sleepiness may have a medical cause. Roughly one-third of all Americans have some type of sleep disorder. People who don't have one, or perhaps don't know that they do, attribute feeling sleepy to heavy meals, boredom, high temperatures, or medication. The truth about sleep needs to be heard, and people need to be educated about sleep before we become a nation of zombies and ruined lives.

Sleep is a biological necessity. So turn off the computer or the TV, put down the phone, pull off the road, and get some shut-eye. To paraphrase Dick Van Dyke, "Stop, drop and sleep!"