The secrets of sleep
It's a mystery, but it clearly makes us smarter and healthier
That's a theory anyway. Another possibility for the morning spike is that endothelial cells--the cells that line blood vessels and are important in preventing clots and narrowing of arteries--don't seem to work as well in the morning. Somers measured this in his lab and found just that: The 6 a.m. level is dramatically lower than at other times of day--comparable to what one would expect to see in a smoker or diabetic.
Chest pains and abnormal heart rhythms also tend to occur during REM sleep. "It's not because REM is bad," says Somers. But if people already have an abnormality in their cardiovascular system, the instability of REM sleep may bring on a disaster. Some blood pressure medications can help keep the heart on an even keel during all phases of sleep and into the morning hours.
Those most at risk for heart problems due to bad sleep are people with apnea, a disease that obstructs the airway. The brain responds by signaling for hyperventilation, and the sleeper breathes harder and faster--heard as snoring. "Every time they do that, it causes a surge in blood pressure and heart rate," says White. Blood pressure can shoot up to 240 over 130, and it can happen dozens, even hundreds, of times a night for years. The damage done over time may put people with apnea at higher risk for hypertension, heart failure, and stroke.
When Douglas Bradley studied people with uncontrollable high blood pressure, he found that fully 85 percent of them suffered from sleep apnea. When treated with a mask that forces air into the airway, blood pressure dropped by 10 points on average. The same treatment can also improve heart function in people with congestive heart failure. The National Heart, Lung, and Blood Institute last year included sleep apnea as an identifiable cause of high blood pressure, but the medical community has been slow to embrace the idea.
The field of cancer treatment is even further behind in recognizing, and using, the body's sleep-wake clock to advantage. William Hrushesky published a paper in Science in 1985 on the circadian timing of cancer chemotherapy. In a group of patients with advanced ovarian cancer, women who took their drugs at one time of day had twice as many complications--and were much more likely to die within five years--as women on a different medication schedule.
Do these differences justify altering standard medical practice? Hrushesky has spent his career trying to answer that question, and his research suggests that the answer is yes. Cancer cells don't die when they're supposed to, and they don't stop dividing. "It's hard to even think about cancer without thinking about timing," says Hrushesky. But few oncologists use what is known about treatment timing. "These ideas may be popping, but they're not in vogue," he says.
Someday, scientists may finally figure out what's so special about sleep, for both the workings of the mind and the body. But until they do, experts say the bottom line remains the same: Get your sleep or suffer the consequences. That's why Erck, the health teacher, has sleep specialists visit her classes to talk to students about the many ways that sleep improves the body and the mind, so that they can start to see a good night's rest as a priority. But sleep still has to compete with the call of work, television, video games, and more; and adults and children alike increasingly find it hard to give shut-eye the respect it deserves. "Unfortunately," says Erck, "most kids and adults don't do the right thing to help them get a better night's sleep."
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