If even just reading this headline makes you yawn, you may be one of the estimated 35% of American adults who, according to the American Academy of Sleep Medicine, don’t get enough sleep because of insomnia. Keep reading to learn what insomnia is and what it means for your health.

What Exactly Is It?

Insomnia doesn’t mean you never sleep, even if it feels that way. (One study found that more than a quarter of people with insomnia get much more sleep than they realize.) The sleep disorder’s definition is much more subtle—and often subjective.

Simply put, insomnia is “dissatisfaction with sleep quantity or quality,” says Joseph M. Dzierzewski, Ph.D., vice president of research and scientific affairs at the National Sleep Foundation, who is based in Washington, D.C. “It is waking up feeling unrefreshed.”

And for most humans, feeling refreshed requires a minimum of seven hours of sleep a night. “Healthy sleep generally means falling asleep within about 15 to 20 minutes of going to bed and sleeping for at least seven hours, with few awakenings each night,” explains James A. Rowley, M.D., professor of pulmonary, critical care and sleep medicine at Wayne State University School of Medicine in Detroit. The reasons for not getting those crucial seven hours might differ—one person may struggle to fall asleep, another may have trouble staying asleep, and still others might wake up too early—but the outcome is the same: sleep deprivation.

During normal sleep, you cycle through what’s known as rapid eye movement (REM) sleep and non-REM sleep. It’s during REM sleep that most dreaming takes place—the eyes dart back and forth, but the rest of the body is still. A stretch of REM sleep can last from 10 to 60 minutes, with each successive REM period getting longer. On average, adults go through five cycles of non-REM and REM sleep in any given night of normal sleep. That doesn’t happen with insomnia.

You may hear the terms “acute” and “chronic” insomnia; the first lasts less than three months, the second persists longer. But if you’re getting insu¢cient sleep for any length of time, it’s worth taking seriously, says Dr. Rowley.

What Causes Insomnia?

Often, sleep troubles beget more sleep troubles. If you’re nervous about falling asleep tonight because you couldn’t fall asleep last night, says Dzierzewski, the anxiety around going to bed can make it that much harder to relax and get adequate zzz’s. That stress can continue to mount, transforming what might have been just a few bad nights into insomnia.

But falling and staying asleep is not always a mental game. Many cases of insomnia are caused by other sleep disorders, such as obstructive sleep apnea (a breathing abnormality) and restless legs syndrome (an uncontrollable urge to move the legs). Or, the cause may be an underlying medical condition: Alzheimer’s disease, anxiety disorders, asthma, chronic autoimmune or pain disorders, chronic obstructive pulmonary disease, depression, heart disease, or Parkinson’s disease, to name a few. Sometimes, the medications for these conditions can interrupt sleep, says Dzierzewski.

Insomnia caused by another health disorder used to be called “secondary insomnia,” while insomnia caused by stress was known as “primary.” But that distinction is no longer considered relevant. “Rigorous research has shown that when insomnia is the direct result of another disorder, it is still deserving of focused attention and treatment and responds well to insomnia treatment,” says Dzierzewski. Plus, the relationship between another health condition and insomnia can go both ways, with insomnia sometimes causing or worsening the health issue.

Finally, lifestyle habits can play a role. Excessive consumption of caffeine, alcohol, or drugs doesn’t do sleep any favors, says Dzierzewski. Neither does “misusing the bed and bedroom,” he says, referring to using them for anything other than sleep and sex. “Think of the bed as a tool designed for sleep, not for working, watching TV, or snacking,” he says. Going to bed at different times every night can also wreak sleep havoc.

Who Is Most at Risk?

The risk factors already discussed aside, some people are more likely to develop insomnia than others. Females are at the top of the list, with a lifetime risk that’s 40% higher than that for males. Why? Women may experience insomnia at higher rates because of a combination of socioeconomic factors, physiological factors like pregnancy and menopause (when hormones are fluctuating), and social contributors like the uneven distribution of childcare responsibilities, says Dzierzewski.

If you’re a woman over age 65, the news is even more disheartening. Older adults are more likely to experience insomnia because they are prone to having underlying health conditions, get less exercise, and have less exposure to daylight, says Dzierzewski. Our sleep undergoes a physiological overhaul, too. As we age, what’s called our “sleep architecture” shifts: We spend less time in the deepest stage of sleep, leading to more frequent overnight wake-ups.

The Effect on Health

Sure, there may be nights—or even weeks—when, because of circumstances (a newborn in the house, for example, or a tough work deadline), you don’t get the full, restorative seven hours. But those nights should be the outliers, says Dzierzewski. Getting less sleep consistently over time will take a big toll on your health, he says. Along with diet and exercise, sleep is the foundation for optimal function of every part of your body, from your brain to the ligaments in your toes. “People with insomnia recover more slowly from injury, experience more pain, are more susceptible to mood disturbances, and experience faster rates of cognitive decline than people who get healthy sleep,” says Dzierzewski.

Need more motivation to take your insomnia seriously? Research shows that the disorder is also associated with hypertension, coronary artery disease, and heart failure. Plus, growing evidence shows that short sleep durations might be at least partially behind this country’s obesity and diabetes epidemics. In men, lack of sleep has been linked to erectile dysfunction and impaired fertility. And research has found that women who had poor-quality sleep showed increased signs of skin aging, including fine lines, uneven pigmentation, and slackening of skin and reduced elasticity, compared with women who had healthy sleep. Beauty sleep, indeed!

The Good News

You don’t have to live with less-than-dreamy sleep. Insomnia can be successfully treated and cured, says Dr. Rowley. Talk with your doctor about what the causes of your insomnia might be and how you can get back to feeling refreshed when you wake up.

This article was originally published May 29, 2019 and most recently updated July 11, 2023.
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