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Research Features

Sweet dreams: Researchers explore link between sleep and health

Feeling sleepy during the day? You’re not alone. Insufficient sleep is a common and fast-growing problem, with almost a third of U.S. adults reporting they get less than the recommended amount of shuteye.  But while some people experience occasional restless nights that still allow them to be alert and productive during the day, many others experience something quite different: a prolonged pattern of irregular, insufficient, and poor-quality sleep that experts say can pose a danger to your heart and to your overall health.

Researchers have associated a persistent lack of sleep with conditions such as heart disease, high blood pressure, diabetes, obesity, and even certain types of cancer. To learn more about why sleep deficiency causes this constellation of problems, researchers funded by the National Heart, Lung, and Blood Institute are looking at how the body regulates breathing during sleep, how sleep deficiencies affect the whole body, and what biomarkers can help assess sleep health. What the researchers discover, they said, could one day lead to better ways to reduce the health risks associated with sleep disorders.

“There are many unanswered scientific questions about how and why people have sleep disorders,” said Michael Twery, Ph.D., director of the NHLBI’s National Center on Sleep Disorders Research (NCSDR). “The good news is that while researchers search for answers, there are many steps you can take to improve the quality and duration of your sleep, which can make you happier and more productive during the day.”  

The NCSDR, which marks its 25th anniversary this year, supports and coordinates sleep science and disorders research, training, and awareness across the National Institutes of Health, other federal agencies, and partner organizations. Based on some of its research, we’ve come up with five important ways you can begin to get better sleep.

1. Establish a regular, relaxing bedtime routine.

It pays to periodically take stock of your “sleep hygiene”—the sleep environment you’ve created and the nighttime habits you’ve adopted over the years. A good place to start: computer screens.  Artificial light from computer screens, whether cell phones, laptops, or televisions, can signal the brain that it’s time to be awake. This light exposure can translate into a loss in sleep duration and irregular sleep schedules in both children and adults. In a study partly funded by NHLBI, researchers showed that smartphone use before bed is associated with shorter sleep duration than normal and worse sleep quality during the night. Studies by other researchers have found similar links. Experts suggest sleep quality can be enhanced by powering down devices at least 30 minutes before getting in bed. Other tips for getting a good night’s sleep include avoiding strenuous exercise just before bedtime and abstaining from alcoholic drinks immediately before turning in for the night.

2. Commit to getting the recommended 7-8 hours of sleep.  (And help your teens get even more.)

Getting the recommended 7-8 hours of sleep each night can be tough for many, but experts say if you create a more relaxing sleeping environment, stick to a regular sleep schedule, and avoid caffeine and other stimulants before bed,  you may be able to hit the mark better.

For many teenagers who often stay up late and wake up early, getting the 8-10 hours recommended for them can be even more challenging. Yet without proper sleep, an NHLBI-funded study recently showed,  teenagers may have a higher likelihood of developing risk factors for heart disease, such as high blood pressure and excess body fat.

 In one of the largest and most comprehensive studies of its kind, scientists tracked the sleep and daytime activity of 829 adolescents for 7-10 days. They evaluated the quantity and quality of sleep, as well as factors related to cardiovascular health—including blood pressure, cholesterol levels, and abdominal fat distribution.  The researchers found that the teens who slept less than 7 hours a night (nearly a third of the participants) tended to have more body fat, elevated blood pressure, and less healthy cholesterol levels.

3. Establish a regular time to go to bed and wake up every day.

Daily schedules can sometimes be unpredictable, but your health will get a boost if you can stick to a consistent sleep pattern. In a recent study funded by NHLBI, researchers reported that having regular go-to-bed and wake-up times can especially benefit the heart.  The study of 1,978 older adults found that those who slept and woke at the same times every day weighed less, had lower blood sugar levels, lower blood pressure, and a lower risk of developing a heart attack or stroke within 10 years, than those with irregular sleep patterns.

How to get on a healthy schedule and stay on it? Decide what time you need to get up each weekday morning, count 7-8 hours backwards, then make that your bedtime. Following that schedule may feel odd and undoable at first, but you can “train” yourself over a period of weeks, by going to bed a few minutes earlier (or later) every night, until you’ve established the habit you want. Then try to keep that same schedule on weekends. If you need to change up, limit the difference to no more than about an hour. Staying up late and sleeping in late on weekends can disrupt your body’s circadian rhythm, the 24-hour internal body clock which controls your sleep/wake cycle.

4. Spend time outside every day (when possible).

Scientists have discovered that daylight is as essential to optimal health as food and exercise. It’s also a key player in optimal sleep. Natural light delivers the entire spectrum of light needed by your eyes and brain to associate daytime with being awake and nighttime with preparing for sleep.  However, traditional indoor lighting produces artificial light that deprives the brain of the type needed to properly prepare our bodies for sleep at night. Similarly, light from TV screens and digital devices can confuse the brain and impede the natural process of preparing for sleep.  If you can’t get plenty of exposure to daylight, consider this: Scientists are developing next-generation LED lighting that could help improve human sleep cycles.  In the future, this new artificial lighting will mimic natural sunlight in a way that is better for your sleep.

While we wait, experts say just go outside for at least 30 minutes each day. If possible, wake up with the sun or use very bright lights in the morning. Sleep experts recommend that, if you have problems falling asleep, you should get a full hour of exposure to morning sunlight, then start dimming the lights inside even before it’s time to go to bed.

5. See a health professional if your sleep doesn’t improve or worsens.

Sleep problems should not be taken lightly and could be a sign of major underlying health issues, including heart disease or cancer.  (They can also put you—and others—at risk while driving or working machinery.) Talk to your doctor if you constantly wake up feeling sluggish and listless, feel sleepy during the day, or cannot adapt to night shift work.

Doctors can diagnose some sleep disorders by asking questions about sleep schedules and habits (such as your use of caffeine, tobacco, alcohol, and any medicines) and by getting information from sleep partners or parents. To diagnose other sleep disorders, doctors also use the results from sleep studies and other medical tests.  If a sleep problem is suspected, doctors can prescribe medicines and other health interventions or even rule out other health or psychiatric problems that may be disturbing your sleep. In some cases, they can refer a patient to a sleep specialist or sleep center for further evaluation.

Common sleep problems include insomnia, sleep apnea, restless legs syndrome, and narcolepsyFor more information about healthy sleep habits, go to the NHLBI’s publication ‘Your Guide to Healthy Sleep.’  Other sleep resources include NHLBI’s special website section entitled ‘Sleep Science and Sleep Disorders.’  Another valuable NHLBI resource is ‘Sleep Deprivation and Deficiency.’

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