Wake up to importance of sleep

Sleep has wide-reaching effects on health


When Paul Harris stays out late on a gig, he usually finds himself "in a fog'' the next day. After getting only four hours' sleep, the 43-year-old musician and social activist says his sin ging voice and creativity suffer.

"I'm not as sharp,'' he says, sipping espresso diluted with decaf in a Baltimore-area coffee shop. "My body isn't running the way it should be.''

Harris has plenty of company. While many of us have trouble getting a good night's sleep, many more scrimp on shut-eye because of work schedules, or simply by choice.

Although some people do fine with less sleep, eight hours is still considered the norm – and there's a price to be paid for not getting it. Recent research indicates that chronic undersleeping does more than undermine productivity or make people more irritable and prone to dozing off. It also increases the risk of accidents and may contribute to serious, long-term problems such as obesity, diabetes and heart disease.

"Ours is a sleep-deprived society,'' says Dr. Steven M. Scharf, medical director of the University of Maryland Sleep Disorders Center. "We know that sleep is essential to life. Deprive rats of sleep, and they die.''

Willingly deprived or not, those who don't get enough sleep may be undermining their health, researchers say.

An American study published this year tracking 71,617 nurses found that women who got five hours of sleep or less nightly over a decade had a 39 per cent greater risk of heart attack than those who managed eight hours.

Oddly, nurses who got nine hours or more also had more heart attacks than the eight-hour group. Dr. David White of Harvard Medical School, one of the study's authors, called that finding puzzling.

"There's not an obvious answer, unless there's some subtle sleep disorder we can't think of that's making them spend nine or 10 hours in bed,'' he said.

The nurses' study was the largest to date linking sleep deprivation with heart disease.

Other short-term lab studies may suggest why it happens.

Scientists at the University of Chicago have found that building up a sleep "debt'' over a matter of days can impair metabolism and disrupt hormone levels. After restricting 11 healthy young adults to four hours' sleep for six nights, researchers found their ability to process glucose (sugar) in the blood had declined – in some cases to the level of diabetics.

The sleep-deprived subjects also showed increased levels of the stress hormone cortisol, which were typical of much older people.

Cortisol is linked to problems that include insulin resistance and memory impairment. So researchers concluded that sleep loss may increase the severity of such age-related chronic health problems as obesity, diabetes and hypertension.

The notion that lack of sleep disturbs the body's chemistry does not surprise sleep specialists, who have concluded that sleep is much more than the absence of being awake.

For example, researchers who scanned sleepers' brains found that the areas involved in learning new tasks remain active in slumber, suggesting that sleep plays a role in storing information for future retrieval.

Many believe sleep helps restore biological processes that are degraded during the day. In deep sleep, for instance, the pituitary gland releases a growth hormone, which helps build bone and muscle tissue. Growth hormone deficiencies, on the other hand, can lead to loss of energy and muscle, and to obesity, research shows.

University of Chicago researchers found that as people age, the proportion of time they spend in deep sleep declines – from 20 per cent for men younger than 25 to less than five per cent in men age 35 and older. Not surprisingly, the production of growth hormone is 75 per cent lower in the 35-and-older group.

Severe sleep "debts'' also tend to alter people's lifestyle in unhealthy ways.

"Basically healthy adults who are acutely sleep-restricted tend to eat more, and what they eat more of tends to be carbohydrates and high in fat,'' says Dr. Carl E. Hunt, director of the National Center on Sleep Disorders Research in Washington.

Few people, though, are aware of how short-changing sleep can affect their ability to function.

One study published this year found that after two weeks of four-hour sleep, a group of healthy young adults performed as poorly on tests of alertness, memory and mental agility as those who had gone without any sleep for two nights. And they didn't seem aware of their gradually deteriorating performance.

Declines in alertness, ability to think and learn have been well documented in sleep-deprivation studies. Those impairments can be dangerous: More than 100,000 auto accidents a year may be fatigue-related, the National Highway Traffic Safety Administration in the U.S. says.

"Our grandmothers told us, 'Get your sleep so you can stay healthy and grow tall,' and we're finding out that's true,'' says Dr. David Neubauer, associate director of the sleep disorders center at Johns Hopkins Hospital's Bayview campus in Baltimore.

Sleep deprivation is a matter of life and death in war. Soldiers in Iraq had to grab naps whenever they could, since they were often on the move at night. Pilots pop "go pills'' to stay alert during sorties – a practice that is the subject of some medical controversy.

Neither is a long-term replacement for regular sleep, experts say.

The causes and remedies for sleep disorders vary. In apnea, the problem may result from weight gain that adds fat tissue around the airways.

Or it may be enlarged tonsils that restrict the flow of air, as Desiree Windsor found after having her sleep monitored at the University of Maryland's sleep lab at Specialty Hospital in Baltimore's Inner Harbour.

"I'm having trouble sleeping at night,'' the 23-year-old day-care worker said, adding that she snores and frequently stops breathing briefly – two symptoms of obstructive sleep apnea.

Removing her tonsils is a likely solution, while other apnea sufferers get help from devices that gently pump air into a mask they wear at night.

Short-term insomnia may be the result of stress, medication side effects or other environmental factors. Chronic insomnia is more complex, and tends to be more common among older people, women and those with a history of depression.

For those who are sleep-deprived by choice, there's a relatively simple solution, says Maryland's Scharf.

"We live in a jazzed-up, overstimulated society,'' he says. "I like the old days, when they played The Star-Spangled Banner (on TV), and everybody went to bed.''

(For more information about sleep deprivation and other sleep disorders, visit these websites: www.nhlbi.nih.gov/about/ncsdr/, www.sleepfoundation.org)


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