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Adequate Sleep As Crucial As Diet
and Exercise For A Healthy Life

Most working blokes know that the more they work, the less they sleep. What they may not know is that the more time they spend in their cars, the less they sleep. Drive time — not television viewing, computer addiction or exercise — is second only to hours on the job as a reason people don't get the shut-eye they need.

"The most deadly combination," says David F. Dinges, chief of the division of sleep and chronobiology at the University of Pennsylvania School of Medicine, "would be long commute time, long work hours and living in a place where you have to get in the car and drive to get anything."

Sound like home?

The combination is deadly because a good night's sleep now appears to be every bit as important to good health and long life as a nutritious diet and regular exercise.

"Sleep is in the top three," says Dinges. "And I think it's No. 1. Sleep is a biological imperative and not getting enough has health-related costs."

In April, the Institute of Medicine issued a report confirming links between sleep deprivation and an increased risk of hypertension, diabetes, obesity, depression, heart attack and stroke.

Some scientists are exploring possible connections between inadequate sleep and a decline in immune function.

The Archives of Internal Medicine devoted its Sept. 18 issue to the relationship between sleep and health. An editorial called for assessment of sleep habits as a standard part of all medical checkups.

That's because short sleep can hasten the arrival of the inevitable long sleep. The largest study of sleep duration and mortality was published in February 2002 in the Archives of General Psychiatry. The Cancer Prevention Study II of the American Cancer Society followed more than a million participants for six years. The best survival was found among those who slept about seven hours a night, the worst among those who slept less than 4.5 hours. Too much sleep — nine hours or more — also was associated with a higher risk of mortality.

In the last decade, researchers have begun studying sleep based on today's reality: a country open for business virtually 24/7, and a populace increasingly unwilling or unable to call it a day. Sleep needs vary slightly, but the vast majority of people, experts agree, need just about eight hours of sleep each night to fully recover from 16 hours of being awake.

Yet Americans are racking up sleep debt like a college kid with a credit card. About 40% of Americans say they get fewer than seven hours of sleep on weekdays, and most — 71% — get fewer than eight hours of sleep, according to a 2005 survey by the National Sleep Foundation. Even on weekends, they sleep about 7.4 hours — better, but not enough to pay back the week's loss. Every hour they fall behind is considered an hour of sleep debt, and Americans accumulate about two full weeks of personal sleep debt a year.

Sleep researchers have a name for the way the vast majority of people in this country sleep: volitional chronic sleep deprivation, and it is a lifestyle disorder.

Without enough sleep, the cost in reduced memory, focus, concentration and reaction time is well established. Incidents in the lore of sleep research include the Exxon Valdez oil spill and the Chernobyl nuclear power plant disaster. In each, key decisions were made by people who were sleep deprived.

But it's only in the last half a dozen years that studies have begun to link chronic partial sleep deprivation to serious physical health consequences.

Command center signals

Sleep is essential to the workings of every organ. And it seems that the connection between sleep and health starts at the brain's central command post, the hypothalamus. There, sleep or lack of it can work to activate, or inhibit, hormone production. There, too, is where the body gets the signal to go to bed, to wake up and to adjust temperature, blood pressure, digestive secretions and immune activity.

Inadequate sleep works on hormone production in other areas as well. Without enough sleep, the central nervous system becomes more active, inhibiting the pancreas from producing adequate insulin, the hormone the body needs to digest glucose.

A groundbreaking study in 1999, led by Eve Van Cauter, a professor of medicine at the University of Chicago, showed that just six days of sleep restricted to four hours pushed 11 healthy young male volunteers into a pre-diabetic state. Those jaw-dropping results expanded the field of sleep research, and convinced scientists that chronic, partial sleep deprivation damaged the body, not just the mind.

The young men in the same study also had reduced levels of the stress hormone cortisol, which normally surges just before waking from a good night's sleep, energizing people for the day's demands. The study participants had the low morning levels of cortisol typical of their grandparents.

And these volunteers also showed that, with chronic inadequate sleep, young people might be accelerating the beer-belly, pear-bottom problems typically linked to middle age. They were producing lower levels of growth hormone after less than a week of four hours of sleep. Growth hormone is largely secreted during the night's first round of deep sleep. As adults age, they naturally spend less time in deep sleep, getting less of the hormone that, in addition to driving childhood growth, plays a role in controlling the body's proportions of fat and muscle.

The University of Chicago study's findings were the first solid evidence that chronic partial sleep deprivation could have physical health consequences. Since then, researchers have begun to look harder and deeper at the links between sleep and illness. A study published in the Dec. 7, 2004, Annals of Internal Medicine found that when 12 healthy, young men were restricted to four hours of sleep for just two nights, normal levels of leptin, a hormone that signals satiety, dropped, while levels of ghrelin, a hormone that prompts appetite, increased.

When the men awoke, following the sleep-deprived state, their hunger and appetite increased — especially for calorie-dense, high carbohydrate foods. "Chronic short sleep is the royal road to diabetes and obesity," says Karine Spiegel, a sleep researcher from Brussels and author of the study. She spoke of her work last June at the annual meeting of the Associated Professional Sleep Societies.

It appears, some researchers believe, that the links between sleep deprivation and obesity are two interacting epidemics. "A few years ago, I would look at obese people and see weakness of character," says Fred Turek, a sleep researcher at Northwestern University and director of the Center of Sleep & Circadian Biology. "Now I believe that if you interfere with sleep, you're interfering with weight. If you interfere with weight, you're interfering with sleep."

The Nurses' Health Study, an epidemiologic study begun in 1976 monitoring the health of more than 100,000 nurses, put poundage to sleep loss. In a study reported in the Aug. 16, 2006, issue of the American Journal of Epidemiology, researchers found that after 12 to 16 years, women who slept, on average, less than five hours per night were 5 1/2 pounds heavier than those who slept an average of seven hours nightly.

The resting heart

The brain controls a lot, but the ever-beating heart needs sleep too. During the night, the heart gets a break. Most people experience a 20% to 30% reduction in blood pressure, and a 10% to 20% drop in heart rate when they're asleep, according to 24-hour blood pressure studies of more than 5,000 people by Dr. William White at the University of Connecticut Health Center.

Sleep is so important for the heart that, in a study published in the Aug. 2 issue of the journal Sleep, researcher Dr. Daniel J. Gottlieb of Boston University School of Medicine suggested that a good night's sleep should be tested as a nonpharmacologic treatment in managing high blood pressure. He questioned more than 5,000 men and women ages 40 to 100 on their sleep habits and found that people sleeping less than six hours had as much as a 66% greater prevalence of hypertension.

"Sleep is good for your heart," says Dr. Virend Somers, a cardiologist and sleep researcher at the Mayo Clinic. "I think physicians should always address the question of sleep with their patients. That's particularly true if they have cardiovascular diseases that are not responding well to treatment."

Those most at risk for heart disease because of sleep problems are people with apnea, a disorder in which airways are obstructed and the person wakes up, sometimes hundreds of times a night, snoring and gasping for air. The sleeper, often unaware of waking, breathes harder and faster during the episodes, and blood pressure and heart rate surge. Sleep apnea puts people at higher risk of heart attack and stroke, in part because their cardiovascular system doesn't get its nightly dose of an easier workload.

A good night's sleep also can stave off short-term illness such as colds and flu, as well as hasten the benefits of a flu shot.

In a study reported in the Sept. 25, 2002, Journal of the American Medical Assn., 25 healthy young men, who normally slept 7.5 to 8.5 hours each night, received flu shots. Eleven of the men were vaccinated on the fourth of five days in which their sleep was restricted to four hours, while the others got their usual nights' sleep. Ten days later, blood tests showed that those who got the shots while sleep deprived had less than half the protective benefits as those who slept normally.

The immune response to the vaccine of sleep-deprived volunteers didn't catch up with that of the well-rested subjects for more than three weeks.

Even some cancers might be rooted in sleep deprivation — or, more precisely, to too many hours exposed to artificial light, according to Richard G. Stevens, cancer researcher at the University of Connecticut Health Center. His work is based on the theory that the increase in breast cancer in the industrialized world is linked to the disruption of hormone cycles.

Light, he says, suppresses production of the hormone melatonin, which allows levels of estrogen to rise. And, when lights are on long after dark, it confuses women's circadian clocks, the roughly 24-hour internal rhythm that keeps hormones and organs on their daily schedule. "Cells don't know when not to divide," he says.

His theory was bolstered by a 1991 Centers for Disease Control and Prevention report showing that blind women are about half as likely as sighted women to get breast cancer. An Oct. 15, 2005, study in Cancer Research looked at sleep patterns of more than 12,000 women. Although researchers found no statistically significant increase in cancer risk among short sleepers, says Stevens, an author of the study, the risk estimates were consistently lower in long sleepers.

"We don't know why breast cancer is increasing in industrialized societies," he says. Until more is known, he advises women to get adequate sleep — and to do it in a very dark room.

It's essential

Adequate sleep may be essential for good health but it's every bit as hard to pull off as eating a healthy, well-balanced diet or finding an hour a day to exercise.

"The most common sleep disorder is insufficient sleep," says Dr. Dennis Nicholson, director of the Pomona Valley Hospital Medical Center's Sleep Disorders Center. "People come in and say they're sleepy. It's because they're not getting enough sleep." The connection seems like a no-brainer, but many people don't see it, he says. They want a sleep study and a pill.

Just as Americans can lay part of the blame for their eating patterns on the food processing industry, and part of the blame for their sedentary lifestyle on unwalkable suburbs and sprawling cities, part of the blame for not quite enough sleep lies with congested highways and homes located far from work.

The University of Pennsylvania's Dinges studied numbers from the U.S. Department of Labor's American Time Use Survey, conducted in 2003, to find what Americans were doing instead of sleeping. He thought that, after time spent working, the next biggest temptation would come from television, computers and entertainment. Not so. "Here's the big surprise. The more time you spend in the car, for any reason, the less you sleep," Dinges said.

Someone who spends a total of 40 minutes in the car each day — that's a round-trip commute plus all daily car errands — gets a good seven to eight hours of sleep. He reported those unpublished findings at the June meeting of Associated Professional Sleep Societies. And he found that for each eight minutes in the car beyond that, sleep time drops by about 15 minutes.

So if a long commute, traffic congestion or a lot of short trips to pick up kids or take dogs to the vet adds just 15 minutes of travel time to that 40 minutes, it means half an hour less sleep. Commuters in the counties of Los Angeles, Ventura, Orange, Riverside and San Bernardino are chalking up hundreds of millions of miles each day on freeways and highways that cover 7,200 miles. It's safe to assume there are a lot of sleep-deprived drivers on the road.

One of them is costume designer Deena Appell, 43, of West Los Angeles. Her day can start with the alarm going off at 4:30 a.m. and take her from one end of the county to the other in a never-ending quest for the perfect shirt, skirt or accessory for characters in a TV series or film. For months at a time, including work on weekends, she might drop into bed around 11 p.m., only to be startled awake 5 1/2 hours later to start all over again.

Appell knows her schedule takes a mental toll. "You really do feel a diminished capacity, like your brain has literally been suctioned out of your head," she says. "And it's not just at night. You're mesmerized by the traffic. I've nodded off at lights, and suddenly you're rolling into the car in front of you. It's not a bad accident. You're just dazed."

The National Highway Traffic Safety Administration estimates that 100,000 accidents and 1,500 traffic fatalities annually are caused by drowsy driving, far more than those attributed to cellphone use. "Those are the people who are driving next to you and me," says Nicholson.

Sleeplessness is a safety issue and a health problem. "Sleep is as important as breathing, drinking and eating," says Dr. Meir Kryger, a sleep scientist at the University of Manitoba. "Animals who are deprived of sleep die, but they don't die because their memory is poor. They die a metabolic death: Their fur falls out, they lose weight. Things that happen are over and above just the brain being sleepy. It's critical to health, but it takes longer to notice."

Reference Source 130
October 11, 2006

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