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March 10, 2017
Chronic Sleep Deficiency Can Lead to Long-Term Health Problems

Not getting enough good quality sleep on a regular schedule does much more than make you sleepy. Over the course of a lifetime, sleep deprivation affects your heart, immune system and emotional well-being, said Dr. Michael Twery at a lecture on Feb. 6 in Bldg. 45.

“Our bodies have evolved to provide the chemistries that support life during the daytime to help us deal with stress during the day and to repair and recover at night,” said Twery, director of NHLBI’s National Center on Sleep Disorders and Research.

Most adults need 7-8 hours of sleep per night. However, the exact amount and schedule for sleep can vary from person to person, he said. When a person goes to bed, a biological process sometimes referred to as circadian rhythm unfolds. This biological clock ticks in any cell with a nucleus—it’s present in everything from microbes to plants to humans.

“It’s controlling our proteins, our genes and the metabolism of cells. And it’s affecting disease pathogenesis,” he explained.

Although it’s unclear exactly why this process happens, evolutionary biologists suspect the circadian clock synchronizes with the availability of light. During the day, a person’s retina detects light and signals the brain that it’s daytime. Eating and exercising also let the brain know when to be awake. At the same time, Twery explained, a person accumulates a neurotransmitter called adenosine while awake. As adenosine levels rise, the urge to sleep increases.

“The urge for sleep is low in the morning and there’s a little bump in the afternoon. And then it goes up again at night, when we want to go to sleep,” Twery said.

Once a person falls asleep, several chemical reactions occur. Some, for example, stimulate the production of hormones that help cells and DNA repair themselves while others help control the body’s use of energy. Skin cells and intestine cells proliferate.

“When we start to deprive ourselves of sleep, it’s not just a matter of less sleep. We don’t complete the pattern. We don’t get all the cycles of sleep. And we don’t secrete the hormones,” he observed. “This snowballs into disease and metabolic problems.”

NHLBI’s Dr. Michael Twery described the effects of sleep deprivation, which can include a variety of long-term health problems.
NHLBI’s Dr. Michael Twery described the effects of sleep deprivation, which can include a variety of long-term health problems.


Staying up late once in a while won’t hurt, but staying up late, getting up early frequently and irregular sleep schedules cause problems. Those who regularly stay up late and wake early are susceptible to heart ailments such as atherosclerosis, coronary heart disease and weakening of the heart muscle. Not enough rest affects the heart’s ability to pump blood and makes it work harder.

Those who are well-rested are motivated, more inspired, have better memories and are able to better regulate their emotions. Sleep-deprived spouses, for instance, might have trouble communicating with each other or their children. Driving a car while drowsy can be very dangerous. Students who sleep through class typically don’t do well in school. Not getting enough sleep “drags everything down.”

Twery warned that naps aren’t a substitute for getting enough sleep at night. While they can remedy the feeling of sleepiness, naps don’t protect a person’s health since they do not support the rhythm of circadian function. The immune system doesn’t get the opportunity to repair itself. Those who are tired may also eat more because food replenishes our emotional reserves.

To get a better night’s sleep, Twery suggested avoiding stimulants such as caffeine and screen time late in the day, taking part in calming activities at night and using as little light as possible before going to bed in a cool, dark and quiet room. There are caveats, though.

“Your vulnerability to artificial light at night—like TV sets and tablets—hinges in part on how much light you get during the day,” he said.

For those who can’t sleep, he advises keeping a sleep diary that can be shared with a physician who can analyze the problem.

Getting enough sleep at night and light during the day is just one component of wellness. People also need to eat a balanced diet and exercise regularly. “All of these activities are tied together,” Twery noted. “You can’t separate them and maintain your health.”

The talk, part of the “Focus on You” series, was sponsored by the Office of Research Services’ Division of Amenities and Transportation Services in partnership with the NIH Health and Wellness Council and NHLBI. It can be seen at

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