Since we were toddlers, old enough to stamp our feet and say “No,” most of us have resisted bedtime. The invention of the light bulb gave us a well-lit world 24 hours a day and with it a host of nighttime seductions: a chance to catch up on reading, work or late-night television. The temptations to stall calling it a day have multiplied in the 21st century: the Internet, 24-hour online shopping possibilities, Words with Friends and social networking, to name a few.
We’ve succumbed. Over the past 40 years, sleep duration among adults in the United States has decreased by one to two hours a night. And a national poll found that 43 percent of Americans say they rarely or never get a good night’s sleep on weeknights.
So it’s time for us all to wake up to the fact that sleep is the necessary third leg of a three-legged stool of well being, every bit as important as the other two legs: healthy diet and regular exercise. To help prevent disease, we also need a good night’s sleep -- about eight hours each night for the average adult. The costs of sleep deprivation in both physical and mental health are just too high to ignore. Maybe it’s not just tots who need, as the best-selling, ribald faux nursery primer advises, to “Go the [bleep] to sleep.”
Eight hours of sleep a night is what most adults need. I know that some of you reading this are thinking that you are the exception. You’re thinking that you’re one of those people who can thrive on six, five, four or even fewer hours of sleep. That’s possible, but uncommon. Research shows that almost all of you who think that way are just kidding yourselves. It’s not that you need less sleep, it’s that you have grown so accustomed to the feeling of sleep deprivation that it seems normal to you.
Slow Reactions, Fuzzy Thinking
A lot of research has been done in sleep laboratories, where scientists can control the amount of sleep subjects get. We know from a vast amount of research that total sleep deprivation -- a night or two of zero sleep -- leads to foul moods, slower reaction time and fuzzy thinking. But is cumulative sleep deprivation, like night after night of four to six hours of sleep instead of a restful eight hours, as bad as a couple of nights of no sleep at all?
Researchers tested that question with 48 healthy adults under constant observation in a sleep lab. All the volunteers were allowed a couple of days of good sleep in the lab to ensure they were well-rested when the experiment began. Then half of them were kept awake for 88 hours, or three and a half days, with no chance to sleep. The other half, divided into three groups, spent two weeks in the sleep lab. One group slept eight hours a night, a second group slept six hours and a third group slept only four hours each night.
All of the volunteers were tested daily for mood and cognition, using standard questionnaires and computer response time tests. Not surprisingly, members of the group that got no sleep for over three days were far less alert and had greater memory lapses than they had before they were deprived of sleep. But what was surprising was that the four-hour sleepers, after just two weeks of that pattern of chronic sleep deprivation, performed just as badly as those who got no sleep at all for 88 hours. Those who got six hours of sleep a night performed worse with every day that passed, though never quite as badly as the four-hour sleepers.
Another group of scientists did a similar study, only they used odd hours of sleep in their tests: five, seven and nine hours each night. They wanted to pin down performance levels between six and eight hours of sleep, and they wanted to know if performance improved with an added hour of sleep. They found little difference in performance when people got nine hours of sleep over those in the above study who got eight hours of sleep; they also found, however, that measures of performance began slipping among volunteers who got only seven hours, compared with those who got eight or nine.
The research is persuasive -- to be at the top of your game, you need eight hours of sleep a night. As one sleep expert once told me: “Sleep is a non-negotiable item.”
Sleeplessness and Weight
It may be counterintuitive to think that inadequate sleep can lead to obesity. After all, when we’re awake, wouldn’t we be more likely to burn additional calories? But a few years ago, researchers showed that inadequate sleep leads to changes in hormones that affect energy and appetite. The less you sleep, they showed, the more likely it is that you’ll be overweight or obese. When 12 healthy, young men (ages 20 to 24) were kept awake for two days, the sleep restriction changed the levels of two important, appetite- and energy-regulating hormones: leptin, which provides energy information to the brain, and ghrelin, a peptide produced by the stomach that stimulates appetite. After just two days of sleep deprivation, the research subjects showed a marked reduction in leptin and an increase in ghrelin. In other words, the body’s communication network was signaling low energy and a need for food. What’s worse, the subjects’ increased hunger resulted in a strong preference for calorie-dense foods with high carbohydrates, a recipe for weight gain.
More recent studies support the association between sleep deprivation, decrease in energy expenditure and weight gain -- whether a total loss of a night or two of sleep, or the more common condition of less than adequate sleep night after night.
During a good night’s sleep, the cardiovascular system gets a break. In most people, blood pressure levels go down by 15 percent to 25 percent as they sleep. Without that break, there is evidence that the heart and arteries can develop damage. But the biggest risk of heart problems from sleeplessness is for people with sleep apnea, a disease that obstructs airways, forcing the sleeper to breathe harder and faster (snoring). It can happen hundreds of times a night, and with each snoring episode heart rate and blood pressure surge. The National Heart Lung and Blood Institute says sleep apnea is the leading cause of excessive daytime sleepiness.
If it’s mild, sleep apnea can be treated with lifestyle changes: lose weight, avoid alcohol and medicine before bed (they make it harder for your throat to stay open during sleep); sleep on your side; quit smoking. For more severe cases, a continuous positive airway pressure machine (CPAP) uses a facial mask and gently blows air into your throat to help keep airways open during sleep. Other options include special mouthpieces that are worn at night to thrust the lower jaw forward, and throat surgery.
Sleep debt, catching up
In places like Los Angeles, where commute times are long and the price of sleeping in can mean hours of wasted time in traffic jams, alarms might go off at 5:30 a.m. or earlier. Working backward, that means a bedtime of 9:30 p.m. to get in eight hours’ sleep; that may seem unrealistic.
But if you work at it, you can catch up. As Bill Clinton said about the economy, getting caught up on sleep is just a matter of “arithmetic.” Say you only get seven hours a night because of your commute. Or you had a particularly busy week, which sliced an hour off your needed eight hours. By the weekend, you’re down five hours. Research has given us the excuse we need to sleep in on the weekends. By getting an additional 2.5 hours on Saturday and Sunday, you should wake up bright-eyed and bushy-tailed on Monday morning.
If you’re more deeply in sleep-debt, it’ll take more than a marathon catch-up over one weekend. You might try tacking on an extra hour each night for several weeks. Or get into the habit of taking a daytime nap. (Nap before 3 p.m., unless you work nights, so you can still get to sleep at night. And keep naps to 45 minutes or less so that waking doesn’t jar you out of a deep phase of sleep.) If your commute is truly horrendous, consider taking a hotel room near your place of work for a night midweek to get caught up on sleep.
Exposure to light before bedtime can slow down our ability to fall asleep by reducing levels of melatonin, the hormone that promotes sleep. Common wisdom still holds: dim lights at night as a preparation for bedtime. Our gadget-infested age, however, adds a new wrinkle: Scientists have found that the blue-light wavelengths have become prevalent in our world -- from LED television sets and computers, smartphone and tablet screens -- and these slow melatonin even more efficiently. And a survey by the National Sleep Foundation found that a whopping 95 percent of us -- people of all ages -- use some type of light-emitting electronic device during the hour before bedtime.
Learning to wind down at the end of a day without a laptop, cellphone or tablet assaulting our retinas is a modern-day challenge. But give it a try. If you can unplug your electronics at least an hour before bed, you might get a night of good sleep. Follow it by another night and another night until you’re in a pattern of good, healthy sleep. You’ll feel like a new person, maybe even like a superhero version of yourself. And that could be the best incentive you have to figure out how to keep a schedule that allows for all the sleep you need.