Are you getting enough sleep?

A sleep shortfall can be hard on your heart. Make sure you're getting enough quality snooze time.

Maybe you stay up past midnight watching TV or checking your smartphone while lounging in bed. Or perhaps you snuggle under the covers and close your eyes at a decent hour, but then toss and turn, unable to fall asleep. Whatever the reason, the results are familiar to many people — feeling unrefreshed and maybe even a bit cranky when you wake up the next morning. According to the CDC, about one in three adults doesn't get enough sleep.

"Some people have trouble falling asleep. But others choose to stay awake and end up chronically sleep deprived," says Dr. Sogol Javaheri, a sleep specialist at Harvard-affiliated Brigham and Women's Hospital. When you don't sleep enough, feeling tired and bleary-eyed is only part of the problem. People who consistently get less than six hours of sleep nightly face a higher risk of heart disease as well as other, often co-occurring conditions such as diabetes and obesity. The exact mechanisms aren't fully understood, but disruptions in blood pressure and blood sugar regulation likely play a role. Insufficient sleep also appears to raise stress hormone levels and inflammation, which also strain the heart.

What causes a sleep deficit?

Sometimes, work or family obligations prevent people from getting enough sleep. But in many cases, habits such as late-night TV binge-watching is to blame, according to Dr. Javaheri. "These people could sleep more if they let themselves, but they don't make it a priority," she says.

Other people have insomnia — trouble falling or staying asleep. These people want to sleep but can't. An estimated 15% to 24% of adults have insomnia, which often (but not always) leads to insufficient sleep. The heart risks associated with insomnia aren't as well defined as the risks from short sleep duration. Part of the reason stems from differences in the way researchers measure and define insomnia, says Dr. Javaheri. However, there is evidence linking insomnia to a greater risk of high blood pressure and heart disease, especially in insomniacs who also don't get sufficient amounts of sleep.

If you're not logging enough z's on a regular basis, a number of strategies can help. Start by taking stock of your nighttime light exposure. "Evolutionarily, we were designed to sleep when it's dark. But now we're flooding ourselves with artificial light late into the evening," says Dr. Javaheri. What's more, the programs people watch on TV or other devices tend to be emotionally stimulating and addicting. They're designed to make you click to the next episode, which often delays your bedtime, she says.

Televisions, computers, and smartphones (as well as energy-efficient lighting) are all increasing our exposure to blue light, one of the wavelengths in the visible light spectrum. Blue light affects the body's circadian rhythm, our natural wake-and-sleep cycle. During the day, blue light stimulates and wakes you up. But too much blue light at night can make it harder to fall asleep. And all visible light suppresses the secretion of melatonin, a hormone that influences circadian rhythms. That's why Dr. Javaheri recommends taking a "technology time-out" and dimming any bright lights for at least an hour or two before bedtime.

Drowsy vs. tired

If you have trouble dropping off to sleep, do something relaxing for at least 15 minutes before climbing into bed, such as reading; listening to a book, podcast, or music; or meditating. Don't get into bed until you're drowsy — that is, when your eyelids feel heavy and you're nodding off and yawning.

"Feeling drowsy or sleepy is different from feeling tired. You can be physically tired but unable to fall asleep," Dr. Javaheri points out. So if you're tired but not drowsy, continue doing a relaxing activity until you do feel drowsy. Stay out of bed so that your brain doesn't link that activity with being in bed; the goal is to train your brain to associate your bed only with sleeping.

Don't look at the clock

If you think you're sleepy but your mind starts racing as soon as you lie down, get out of bed. Do something relaxing until you actually feel drowsy. The same advice applies if you wake up at 3 a.m. and can't fall back asleep. Don't keep checking the clock, watching the time tick by. You'll just become frustrated, further foiling your attempts to sleep, Dr. Javaheri says. If you end up sleeping only for a few hours, remind yourself that it's not the end of the world. You'll probably catch up on your sleep over the following day or so, she adds. But if you don't, and if sleepless nights are the norm, consider checking out a more structured approach to combating insomnia (see "CBT for insomnia").

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