Sleep deprivation can make you careless, vulnerable to illness -- and it can accelerate aging.
More than 100 million Americans of all ages fail to get a good night's sleep, at least occasionally. And we are suffering for it: from heart disease to depression to "accelerated" aging, the latest condition tied to sleeplessness. Yet bypassing bedtime is considered a virtue in corporate America, where high-powered executives crow about their five or fewer hours of sleep.
Though the average adult gets 6 hours and 58 minutes of Zzzs nightly, we actually need at least one hour more, sleep experts say. Only 35 percent reach the desired goal of eight hours.
Starting at age 40, our deep, restorative sleep begins to decrease. Shut-eye becomes disrupted due to medications, pain, arthritis, and other health problems. Our internal clocks also send us to bed and wake us up earlier. Yet while sleep may be tougher to get, our need for it doesn't decrease.
Even the sleep we do get isn't much to boast about: Two-thirds of us complain about having insomnia a few nights or more a week, reports the latest National Sleep Foundation poll. The complaints: waking up unrefreshed, struggling to fall asleep, rousing repeatedly during the night, or rising early and being unable to return to sleep. At least 42 percent of Americans are so sleep-deprived that it harms their work and relationships.
You may seem completely out of it as you snooze, but deep within, your body works overtime. Your body alternates between 90-minute to 2-hour cycles of deep, or slow-wave, sleep and REM, or rapid eye movement sleep. During deep sleep, organs, bones, and tissues are repaired, while during REM, emotions and memories are processed. For the greatest benefit, you need at least eight hours of sleep with a high percentage of deep sleep in the first two hours and mostly REM sleep in the last two hours, says James B. Maas, Ph.D., a Cornell University psychology professor in Ithaca, New York.
Throughout the night, your body tunes itself up, recharging your batteries, resetting your thermostats, and topping your fluids so you can operate at your peak. Your brain is the conductor, refurbishing your worn organs, burning calories, releasing hormones (including growth hormone, which builds muscle), and processing and storing the day's memories and lessons. All of your body's parts play their roles with the well-timed precision of a symphony orchestra. Instead of a major finale, this concert ends when your biological clock registers that you've paid off any sleep debt accumulated to that point.
Interrupt the performance too early and you lose your rhythm. "The consequences are crankiness; slowed reaction time; hampered creativity; inability to remember, analyze, do math, or make decisions; and most of all, daytime drowsiness," says Maas, author of the book Power Sleep (Harper Collins, 1999). "Sleep deprivation makes you stupid."
You might drop your dishes in the clothes dryer and not realize it until you turn the machine on and they shatter. You may fall asleep at a red light, waking only when the driver behind you honks. Or you could fall asleep during sex -- not exactly conducive to romance. All have happened to sleep experts' patients. "The real danger is that we don't realize we're tired," says David Dinges, Ph.D., a sleep researcher at the University of Pennsylvania in Philadelphia. "We'll go about our business as if we were capable."
To return to full capacity, we've got to repay our sleep deficit. Indeed, Dinges says, sleep debt is much like a financial one. Once you've robbed your dozing bank, you've got to refill it with the same amount, ideally by oversleeping for days in a row.
An inadequate amount of sleep can shorten your life in more ways than one. A University of Chicago study of 11 healthy men, ages 17 to 28, found that when their sleep was restricted to four hours for six nights in a row, they aged rapidly. Their levels of hypertension, diabetes, and memory problems rose to levels usually associated with 60-year-olds. Fortunately, as reported in the British medical journal Lancet, the subjects were refreshed after a few nights of 12-hour slumber.
Growing evidence shows that a lack of sleep makes us more vulnerable to infection, as well as high blood pressure, anxiety, weight gain, and stress. Insomniacs have a 40 percent higher risk of developing depression, says Gary Zammit, Ph.D., director of the Sleep Disorders Institute at St. Luke's Roosevelt and Beth Israel Hospital in New York. "To put it in perspective: You can eat, drink, or have sex in just a few minutes, but in order to satisfy your sleep needs, you require an extended period every day. Either sleep is Mother Nature's greatest mistake, or it serves a critical function."
Sleep deprivation causes an estimated 100,000 accidents a year on the road, according to the National Transportation and Safety Board. Insomniacs are 3.5 to 4 times as likely to be in a car accident and 1.5 times more likely to be in a workplace accident. In one survey, more than half of North Carolina drivers who had been in a car accident had slept less than six hours the previous night.
Adding alcohol can be lethal, author Maas says. "Having one drink of alcohol on six hours of sleep affects your ability to drive the same as if you'd had six drinks on eight hours of sleep that night."
With or without the added impact of alcohol, "If you don't take sleep deprivation seriously, you'll pay the price," warns sleep researcher David Dinges.
The best way to get maximum rest is to practice the following:
If you suffer insomnia for more than three weeks, keep a sleep diary for four to seven days to show your doctor. Record the time you went to bed, fell asleep, woke up during the night, how you felt in the morning, and the timing of drinks and exercise.
Your doctor may prescribe -- usually for less than a month's duration -- drugs such as newly developed Ambien and Sonata, both of which leave the body quickly so you're not groggy in the morning.
The more your body is growing, the more slumber you need. Infants doze 16 or more hours a day; 3-year-olds only 12 hours. From puberty to age 20, a child needs 9 hours and 15 minutes.
Unfortunately, American teenagers only average six hours. "We're trying to educate a nation of walking zombies," says James B. Maas, Ph.D., Cornell University psychology professor and author of Power Sleep (Harper Collins, 1999). "Students' bodies are in the classroom, but their brains are on the pillow at home."
Perhaps this is a case of too much to do and too little time, but it also may be one of biology. Teenagers' internal clocks shift at puberty, sending them to bed two hours later, at 11 p.m. In 1998, federal legislation was introduced to offer school districts financial incentives to change school hours to be more in sync with teens' circadian rhythms, but only a few communities did so.
Studies by the nation's leading teen sleep researchers show:
The sleep your child is missing matters. Hormones essential to growth and sexual maturation are released during sleep. The brain also clears short-term memory, reviews the day's learning, and reboots emotions during REM, or rapid eye movement sleep (so-called because eyes dart back and forth under the lids). "The old adage that teenagers who don't sleep don't grow has some truth to it," says Dr. Frisca Yan-Go, medical director of the UCLA Sleep Disorders Center.
The longer you sleep, the better your grades. A survey of 3,120 Rhode Island students found that students earning As and Bs averaged 35 minutes more sleep a night than those earning Ds and Fs. One-fourth of the students slept 6-1/2 hours or less on school nights. Only 15 percent slept 8-1/2 hours or more.
Inadequate sleep leads to poor concentration, inability to remember, crankiness, and sluggishness. It's also a major reason that car accidents are the second leading cause of death in young people, Dr. Yan-Go says. So what can you do?
Originally published in Better Homes & Gardens magazine, September 2000.