SEPTEMBER / OCTOBER 2004

AROUND HARVARD

This article originally appeared in the August 2004 Harvard Heart Health Letter and is provided courtesy of Harvard Health Publications.

Wake-up call for better sleep

Add a good night’s sleep to the healthful things you can do for your heart.

Whether you look forward to your nightly sleep — “Nature’s soft nurse,” as Shakespeare called it — or, like novelist Virginia Woolf, regard it as “that deplorable curtailment of the joy of life,” one thing is certain: Problems sleeping are more than just an aggravating end to the day.

Beyond making you drowsy during the morning and afternoon, not getting enough sleep night after night can contribute to high blood pressure, heart disease, and sudden death. New evidence also links it with diabetes and difficulty controlling weight.

How much sleep is enough? The answer varies from person to person. Some people say they flourish with just five or six hours a night; others need nine or more to feel their best. But for most of us average Joes and Josephines, eight hours keeps coming up as the magic sleep number in the latest research.

Changes during sleep
In Greek mythology, Thanatos (death) and Hypnos (sleep) were brothers. Although sleep may look like death, its placid exterior shrouds a system hard at work repairing, regenerating, recuperating, and preparing for a new day.

Sleep is an elaborately scripted play that wanders across four distinct stages. There’s the transition from wakefulness to light sleep (stage 1), a slowdown in breathing and heart rate while the brain is still somewhat alert (stage 2), and deep sleep, some of it with the rapid eye movements that signal dreaming (stages 3 and 4).

It’s this deep sleep that’s most important for waking up refreshed. During much of deep sleep, blood pressure gradually sinks and the heartbeat slows. Except when you are dreaming. During dreams, rapid changes in brain chemistry cause surges of stress hormones. As a result, your blood pressure and heart rate fluctuate, your eyes dart in all directions, and your brain races. Dreaming has such a profound effect on the heart that Harvard scientists once proposed that this period of sleep could act as a stress test for the heart and possibly identify people at risk for cardiac arrest.

Sleep is easy to put off and just as easily disrupted. A survey by the National Sleep Foundation suggests that about half of American adults borrow from sleep to get more work done, watch late-night television, or surf the Internet. Anxiety about a doctor visit or worrying about a loved one can keep you awake, as can pain from an illness or injury. Conditions such as sleep apnea (see Sleep apnea below), leg cramps or movements, heart failure, and many others can also interfere with sleep. Alcohol, caffeine, poorly timed exercise, even saggy mattresses contribute to the American sleep debt. Our national average, around 9–10 hours of sleep per night a century ago, has fallen to under 7 hours today.

Sleep and disease
Over the short term, not getting enough sleep boosts blood pressure and stress hormone levels. Sleep deprivation makes it difficult for the body to process blood sugar and reduces levels of leptin, an appetite-depressing hormone. These two changes could lead to diabetes and weight gain. It also increases inflammation, thought to be a key element in the development of heart disease. Long-term lack of sleep rolls these into a variety of ills.

Premature death. In a six-year study of more than a million adult Americans, deaths were more common among those who reported averaging less than 4.5 hours or more than 8.5 hours of sleep a night.

Heart disease. In a long-running study of initially healthy female nurses, almost 2% of those who said they slept less than five hours a night developed heart disease over a 10-year stretch, compared with 1.1% of those who reported sleeping seven to eight hours a night. Those sleeping more than nine hours a night were also at increased risk.

Diabetes. Similar increases in diabetes were also seen in the nurses’ study.

None of these studies, or the others published over the last few years, offer bullet-proof evidence that being sleepless in Seattle or anyplace else causes heart disease or diabetes or shortens life. Still, the evidence strongly tilts toward a connection between sleep trouble and heart disease.

Tips to better sleep
If you’ve had trouble sleeping, getting back on track takes some sleuthing. You’ll need to look at what you eat and drink, your sleeping environment, and nighttime habits for clues to the problem.

Here are several common remedies for better sleep:

 Help reset your internal clock by establishing a regular bedtime schedule.

 Alcohol may make you drowsy, but it also makes you waken more easily later on. Skip the nightcap or cut back on drinks with dinner to see if your sleep improves.

 Regular exercise can aid a good night’s sleep. Late afternoon activity seems to be best; avoid exercising within three hours of bedtime.

 If you drink coffee, tea, or other caffeinated beverages, try cutting back on them, or at least not having any after noon or midafternoon.

 If the need to urinate at night fractures your sleep, try drinking more fluids in the morning and afternoon and limiting your fluids from dinnertime onward.

 Mattresses and pillows don’t last forever. Check yours to make sure they’re giving you the support you need.

It’s time to wake up to the fact that a good night’s sleep isn’t a luxury but, like healthy eating and exercise, helps set the stage for better cardiovascular and overall health.

Sleep apnea: The pause that de-freshes
For a particular type of snoring, the suspense — and the suspension — are the killers.

Millions of sleepers temporarily stop breathing dozens or hundreds of times a night. The pauses can keep a bed partner awake worrying that the sleeper has stopped breathing for good; the explosive gasps that follow, though reassuring, compound the problem. The pauses and gasps are even harder on the snorer, who seems blissfully unaware of the trouble but pays for it later. These breathing problems are a prime cause of daytime drowsiness. They are also a likely source of some sudden deaths and contribute to cardiovascular disease and other chronic conditions.

Sleep apnea (AP-knee-uh) is the term for temporary interruptions in breathing during sleep. Most of this is obstructive sleep apnea, which happens when tissues in the throat periodically block the airway. Some people suffer from central sleep apnea, a failure of the brain to send the proper messages to muscles that automatically breathe for you at night.

Although sleep apnea is often portrayed as a condition of overweight men, it isn’t nearly so limited. Women make up a third of sleep apnea sufferers, and thin people can develop it, too.

The emergency “Breathe now!” signal the body sends to restart air flow involves the same nerve pathways and hormones that get fired up when you are frightened (the sympathetic nervous system). Unfortunately, their effects extend far beyond the nerves and muscles needed to breathe. Increased activity of these pathways and hormones boosts blood pressure. It can also provoke disturbed heart rhythms and reduce blood flow to the brain.

How do you know if you have sleep apnea? Common signs include:

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