Author: Sheldon H. Gottlieb
Source: Diabetes Forecast, Your Healthy Heart, August, 2003
“Can you give me something to help me sleep?” is a question that just about every health care worker dreads.
Before reaching for the prescription pad, I try to persuade my patients to have a bedside library, a few favorite books that they can briefly dip into before falling asleep. One of my bedside favorites is Robert Pirsig’s Zen And The Art Of Motorcycle Maintenance. This is a fascinating book about the quality maintenance of an important machine–ourselves. It also touches on the critical role of sleep in a personal maintenance program.
Does sleep refresh the brain or the body? The traditional answer–that we sleep to refresh the brain–is implied by the definition of “sleep” in the 1989 edition of the Oxford English Dictionary: “the unconscious state or condition regularly and naturally assumed by man and animals, during which the activity of the nervous system is almost or entirely suspended, and recuperation of its powers takes place.”
But sleep refreshes the body as well as the mind.
Sleep is controlled by a body clock in the brain that scientists call the circadian clock. The internal clock is named “circadian” from the Latin circa, which means “about” and dies, which means “day.” The first clock was the Earth, making one “tick” or revolution, every 24 hours.
The earliest living organisms, the blue-green algae, began tuning in to this daily rhythm, capturing sunlight and combining it with carbon dioxide to produce glucose and oxygen, during the daylight hours. From one-celled plants to poets, most living things on this planet remain internally in synch with this 24-hour clock.
A scientist from the University of Cambridge, Michael H. Hastings, describes the body clock as follows: “Circadian clocks have a powerful influence on when we enter and leave this world…. Spontaneous births are most prevalent at night, myocardial infarcts and strokes occur most often in the morning, and metabolic functions change progressively and predictably over the 24 [hour] cycle.” In Russian folklore, as expressed by the movie director Ingmar Bergman, the circadian cycle reaches its lowest point in the quiet hour before the dawn, “the hour of the wolf, when old men die, and little babies are born.”
How much sleep do people need? Most need 6 1/2 to 9 hours of sleep each day. When our lives were more closely tied to the rhythm of the sun and the seasons, getting this much sleep was not a problem. Today, however, many people do not get the sleep they need for many reasons, including hectic work-lives (especially those who do shiftwork), and the distractions of television and the Internet.
But there is a price to be paid for this: Research has shown that a lack of sleep causes a “sleep debt,” which increases insulin resistance and causes more stress hormones to be released. The result: higher blood sugar levels.
In humans, the body clock begins to increase the concentration of blood sugar just as day is dawning. This familiar early morning spike in blood sugar, known as the “dawn effect,” seems to have survival value by preparing us for the stress of the day. For many years this morning rise in blood sugars was thought to be caused by increased secretion of growth hormone in the predawn hours. Recent research, however, has shown that the circadian clock in our brain may also play a part, by signaling the liver to increase its output of glucose; it may also signal the body’s tissues to take in more glucose in the early morning hours as well.
In the comics, snoring is usually represented by a large woodcutter’s saw spitting out sawdust, producing a chain of “Zs.” It’s ironic that sawing wood was chosen to represent snoring, since sawing wood is hard work, which increases oxygen consumption, whereas snoring is a sleep disorder associated with periodic decreases in oxygen.
Obesity, neck size, snoring, and advanced age are associated with sleep disorders. About 40 to 60 percent of mildly to moderately obese people have sleep-disordered breathing; about 34 percent of football players who are defensive lineman (average neck size, 19.1 inches) have disordered breathing, even though their average age is only 25.
People who snore and have sleep-disordered breathing are at an increased risk for daytime drowsiness, confused thinking, car wrecks, and impotence. And if that doesn’t seem bad enough, they are also at increased risk for developing insulin resistance and type 2 diabetes, hypertension, and coronary heart disease.
So how can people with diabetes get a better night’s sleep?
Those taking insulin should review their blood sugar records, diets, and activity levels with their health care providers. The patterns revealed may offer clues on ways to better adjust their dosing schedule or whether, perhaps, the type of insulin they are using should be changed.
Another clue that something is wrong is frequent nighttime low blood sugars (hypoglycemia). Often, low blood sugars are not sensed by people when they sleep, but they’ll know they had them in the morning because they’ll awake with headache and may feel drowsy during the day. If middle-of-the-night low blood sugars are recognized and treated with too large a snack, then the morning blood sugars may soar out of control after awakening. To compound matters, if a person experiences frequent low blood sugars, it can lead to a condition known as hypoglycemia unawareness, which can lead, in turn, to very severe low blood sugars.
Some studies have shown that the use of regular insulin before dinner and NPH at bedtime can reduce nighttime low blood sugars. But everyone is different: If you’re having trouble with nighttime lows, be sure to discuss all your options with your health care provider.
For those who snore, weight loss–as little as 10 percent of total body weight–is associated with improved glucose tolerance and lessened sleep-disordered breathing. Continuous air pressure, delivered by nasal prongs or by a mask attached to a device called a CPAP (Continuous Positive Airway Pressure) machine, is often effective in reducing snoring and improving sleep quality. Keeping to a regular schedule of sleep, meals, and exercise will also help to improve sleep quality and reduce the risk factors of heart disease.
Unforgiving machines like motorcycles need high-quality maintenance. And so do our bodies. Your maintenance program should begin with a good night’s sleep.
Sheldon H. Gottlieb, MD, FACC, is a cardiologist at Johns Hopkins Bayview Medical Center, Department of Cardiology, in Baltimore, Md. He also directs the Diabetes-Heart Failure Program at Johns Hopkins HealthCare, LLC.