For more than 25 years, scientists at NIH have studied human sleep habits. They've researched everything from how sleep affects our skin to how it could help us live longer.

"Feeling tired may not be the best way to measure where your sleep health may be."

- Michael Twery, Ph.D.

A major focus of current NIH-supported sleep research is on our circadian rhythm, the body's natural 24-hour cycle.

"When people don't get enough sleep, they don't get a strong circadian rhythm," says Michael Twery, Ph.D. Dr. Twery leads sleep research at the National Heart, Lung, and Blood Institute.

"And if we don't have a strong circadian rhythm, the cells in our body don't get enough energy," he adds.

Why is that important?

The circadian rhythm operates within every cell of the body. Poor quality sleep or not enough sleep affects these cells, including fat cells and those in the heart, liver, and kidneys.

This may contribute to poor health and an increase of risk of disease, like heart conditions, diabetes, or even death.

Heart disease and sleep

NIH's National Center on Sleep Disorders Research has supported the discovery of sleep and circadian rhythm regulating genes. By better understanding how genes work in the human body, we can better understand why a lack of sleep can cause certain problems. 

For example, NIH-supported researchers are now closer to understanding how a good night's sleep can protect against some types of heart disease.

They have discovered a connection between the brain, bone marrow, and blood vessels that can protect against hardening of the arteries—but only when sleep is uninterrupted.

When our arteries harden, that restricts blood flow to our heart. This can lead to heart attacks and strokes.

By better understanding the connection between sleep and hardening of the arteries, this research could open new avenues to treat heart disease.

Pregnancy and sleep apnea

Other NIH-supported studies are finding that lack of sleep is more likely to affect women who experience hormonal changes like menstruation, pregnancy, and menopause.

Dr. Twery's team organized studies to determine whether treating sleep apnea—which disrupts sleep and can cause breathing issues—may reduce health risks in pregnant women. Those risks include hypertension and diabetes.

Their research found that breathing issues during sleep are common in pregnancy. They're also associated with bigger health risks to the pregnant woman, often resulting in health complications.

But strong medications can be dangerous for pregnant women, so his team is now studying how to protect breathing in other ways.

"The current medical tools are limited," Dr. Twery says.

The power of sleep

proper sleep also leads to healthy brain development and growth hormones, which helps our bodies perform at their best.

"Feeling tired may not be the best way to measure where your sleep health may be," Dr. Twery says. "Most people go to sleep when they feel tired, but the brain doesn't go to sleep."

Because of that, interrupted sleep can impact our brains more than we might realize, causing issues like memory loss, mood changes, or difficulty concentrating.

Lack of sleep and sleep disorders can also create problems in people's personal lives, especially within their families, Dr. Twery says. It can affect how people perform at work or school.

His advice is to prioritize sleep and seek help from your doctor if you regularly experience interrupted sleep, an inability to fall asleep, or other sleep issues that are affecting your quality of life.

Your physician may determine whether further tests are needed to understand the sleep problem and how to manage treatment.

"We talk about sleep as a luxury today and our society tells us to stay awake. It's even celebrated as a super-human quality," Dr. Twery says.

But for those who are trying to "do it all" and sleep less than the recommended hours per night, Dr. Twery cautions that sleep is essential to a long, healthy life.

"Our brains and bodies are very complicated," Dr. Twery says. "Get some sleep."