Air traffic controllers falling asleep on the job have been in the news with alarming frequency lately. In addition to the obvious dangers of falling asleep at the switch or not performing at your peak because of daytime sleepiness, prolonged sleep deprivation can have serious health consequences—including the health of your heart.
Air traffic controllers aren't the only ones at risk. Emerging research suggests that anyone who suffers from sleep deprivation may be at increased risk of developing cardiovascular disease (CVD), including heart attack and stroke.
Here are four common culprits and how they may pose a threat to your heart health:
INSUFFICIENT SLEEP: Most healthy adults need 7 to 8 hours of sleep in order to feel and function their best. People who habitually get less sleep generally feel tired and irritable, and often have problems with concentration and memory.
Insufficient sleepers fall into two groups. One group is sleep-deprived because of life circumstances—they work long hours or multiple jobs, travel a lot or have other issues that force them to stay up, says Pete Bils, instructor in sleep physiology at Northwestern Health Sciences University in Minneapolis. The second group chooses to forego sleep in favor of other activities, such as watching TV, Web surfing or video chatting, adds Virend Somers, M.D., professor of medicine and a consultant in cardiovascular diseases at the Mayo Clinic in Rochester, MN.
Whichever one describes you, studies suggest that short sleepers may be courting a heart attack, warns Atul Malhotra, M.D., medical director of the sleep disorders research program at Brigham & Women's Hospital in Boston. For example, the Nurses' Health Study—one of the largest and longest-running investigations of factors influencing women's health—found that the risk of heart attack in women who sleep 5 or fewer hours a day on a regular basis is significantly higher than that of women who sleep a full night.
According to the National Sleep Foundation, one-quarter of American adults—that's 47 million of us—don't get the minimum amount of sleep required to be alert the next day. Experts say insufficient sleep exerts its damaging effects in a variety of ways.
Lack of sleep causes levels of adrenaline (known as the “fight or flight” hormone) and cortisol (the so-called “stress” hormone) to surge. In addition, normal nighttime dips in heart rate and blood pressure don't occur in those who aren't in bed sleeping as long as they should. As a result, the body remains in a state of arousal, preventing deep, restorative sleep.
When you're tired, you tend to fuel yourself with extra calories to keep going. Insufficient sleep “wreaks havoc on your ability to manage your appetite,” says Bils. In people who are sleep-deprived, production of a hormone that tells your brain when you've eaten enough (leptin) falls, while production of a hormone that tells your brain you need another helping (ghrelin) increases.
To make matters worse, the extra calories will likely come from cookies, cake and other foods that are high in simple carbohydrates. When you don't sleep enough, “You also tend to have less willpower and energy, so you're less likely to work out,” adds Bils. This can lead to what he calls “a horrific cycle” in which poor sleep leads to weight gain that further boosts CVD risk.
INSOMNIA: Generally defined as a chronic inability to fall or stay asleep, insomnia is the most common sleep disorder; 54 percent of Americans experience insomnia one or more days of the week. Insomnia may stem from one of two basic causes, says Somers. Some cases of insomnia are caused by an underlying physical ailment, such as obstructive sleep apnea, chest pain or heart failure. Or a person may be kept awake by anxiety or depression.
Either way, insomnia affects the body the same way insufficient sleep does. If you don't get enough sleep, you may eat more than you should, be too tired to engage in regular physical activity and, as a result, gain weight and develop high blood pressure and other risk factors for CVD.
OBSTRUCTIVE SLEEP APNEA (OSA): Characterized by repeated breathing pauses during sleep, OSA is caused by excess tissue blocking the airway. In some cases the excess tissue may be swollen tonsils or adenoids, in others it may be fat deposits in the upper airway collapsing into the back in the throat. Because air is trying to squeeze past the obstruction, people with OSA often snore loudly enough to wake their bed partners, who may also witness them gasping for breath.
About 18 million Americans have OSA, which has been linked to atrial fibrillation, heart attack and sudden death. When breathing stops, explains Somers, there is less oxygen and more carbon dioxide in the blood. This causes blood vessels to constrict, which raises blood pressure. Low blood-oxygen levels also may prevent cells that line blood-vessel walls from producing nitric oxide, which keeps the walls of blood vessels from narrowing and stiffening. That, adds Somers, may be a factor in the long-term development of CVD.
RESTLESS LEGS SYNDROME (RLS): As many as 12 million Americans experience unpleasant tingly sensations in their legs when they lie down to sleep, which triggers a need to incessantly move their legs the way an itch makes you want to scratch.
RLS may be a sign that the sympathetic nervous system, which regulates key body functions such as heart rate and blood pressure, is working in overdrive. A hyperactive sympathetic nervous system can accelerate heart rhythm and constrict blood vessels to cause high blood pressure, both of which may increase risk of heart attack and stroke.
ENTER THE SANDMAN
So is chronic lack of sleep as important a risk factor for CVD as a couch-potato lifestyle or a junk-food diet? Research on sleep and CVD risk “is relatively new,” Somers says, adding that additional studies are needed to accumulate the evidence needed to conclusively link a specific sleep disorder with an adverse cardiovascular effect.
In the meantime, though, effective treatment for sleep disorders depends on the underlying cause. If a health problem is keeping you awake at night, proper diagnosis and treatment are the first steps toward improving your sleep. If your sleep problems are due to lifestyle factors, you may have to change your attitude about bedtime. [For more information about getting the rest you need, visit www.HeartInsight.com to read “Can You Buy a Good Night's Sleep?”]
Here are suggestions to help speed you to slumberland:
1. Make sleep a priority. Instead of fitting sleep into whatever time remains after you take care of everything else, carve out 7½ to 8 hours a night, and build the rest of your life around a regular sleep schedule. Be aware, too, that sleeping late on weekends can't make up for days of sleep deprivation. It's important to get enough sleep every night of the week.
2. Wind down. For at least 45 to 60 minutes before turning in, avoid computers, TVs, iPads, iPhones and video games. Their screens emit light that may suppress production of melatonin, a hormone made by the pineal gland in the brain that helps regulate the sleep-wake cycle.
3. Don't rely on pills. Prescription or over-the-counter sleeping aids may be helpful during periods of severe stress, but these drugs produce sleep that's less restorative than natural sleep. Sleep aids also may have side effects, including morning grogginess and withdrawal symptoms.
4. Limit caffeine. Avoid caffeinated beverages such as coffee, tea and energy drinks after noon. Caffeine has a lengthy “half life,” which means it remains in your body for several hours. Even if you are able to fall asleep after a Starbucks run, your sleep won't be as deep as it should be.
5. Eat smart. Stick to a balanced diet that includes foods containing tryptophan, an essential amino acid that helps regulate sleep. Tryptophan-rich foods include poultry, seafood, low-fat cheese, low-fat and nonfat milk, and whole grains. Also, eat your last meal of the day at least 2 to 3 hours before bed to avoid acid reflux and other digestive problems.
6. Exercise early. Everything about exercise is good for sleep—except when you work out shortly before bed. That's because working out boosts your heart rate and body temperature, both of which must fall before you can drift off to sleep.
7. Turn your bedroom into a sleep zone. Keep your bedroom as dark as possible; if you need to go to the bathroom, get a dim nightlight to guide you, since even brief exposure to light can tamp down melatonin. Use your bed only for sleep and sex, not for reading, working or watching TV. Keep the room temperature at 65º F.
8. Get the right bedding. Your sleep posture determines the type of pillow you need. For example, side sleepers need more substantial pillows than back-sleepers do. Be aware that our bodies change over time. If you gain or lose weight, get pregnant or develop acid reflux or another medical condition that causes you to sleep in a different position, you may need to invest in a new pillow or mattress. Always talk to a knowledgeable salesperson before you buy new bedding.
Following these sleep-tight tips will not only help you feel more alert and cheerful during your waking hours, they may also help prevent a cardiovascular nightmare down the road.
© 2011 American Heart Association, Inc.