Science 101

What Is a Sleep Disorder?

Chronic sleep loss can contribute to health problems and speed up the aging process. Here’s why — and how to improve your slumber.

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Everyone has experienced a night spent tossing or turning or waking at 2am to stare at the ceiling for hours. But for many, not getting enough zzzz’s is a frequent nightmare, with health consequences that extend far beyond next-day grogginess.

“People who regularly get fewer than six hours sleep a night are about 30 percent more likely to become diabetic, around 20 percent more likely to develop high blood pressure, and are more likely to gain weight and have inflammation,” said Michael Grandner, Ph.D., director of the Sleep and Health Research Program and an assistant professor in the Department of Psychiatry at the University of Arizona College of Medicine in Tucson. “They’re also more likely to have substance problems, depression, and accidents.”

One third of Americans fall into this six-hours-or-less-a-night category, according to recent findings published in the journal Sleep. Some of these people may just stay up too late binge-watching Netflix, but others likely have a sleep disorder.

Broadly speaking, sleep disorders are defined as any problem that affects amount, timing, or quality of sleep, Grandner said. There are more than 80 distinct disorders, ranging from the familiar (like restless leg syndrome) to the rare (such as sleep terrors, a condition in which a sleeping individual reacts to a sense of fear by screaming or thrashing around). But the two most common by far are insomnia and obstructive sleep apnea.

As many as 70 million people have a sleep disorder. One in three people have at least a mild form of insomnia, while 25 million U.S. adults have obstructive sleep apnea. To understand the true scope of those figures, it’s important to understand what those conditions look like, day-to-day — or more importantly, night-to-night.


As many as 15 percent of adults have chronic insomnia, meaning they take more than 30 minutes to fall asleep, or wake more than three times a night (for more than a total of 30 minutes) more than three times a week, for more than three months.

People with insomnia may struggle to fall asleep, or they might nod off easily only to rouse in the middle of the night and not be able to get back to sleep for hours. Others wake far before the alarm is set to go off. The most unlucky insomniacs suffer a combination of these problems, Grandner said.

Insomnia is linked to higher blood pressure and systemic inflammation, Grandner said, which may explain why multiple studies show an association between the disorder and stroke, coronary heart disease, and cardiovascular disease.

Chronic insomnia can also wreak havoc on your mental health. A lack of sleep makes stress and anxiety worse, and increases the risk for depression. “Insomnia is an even better predictor of depression than a depressed mood,” Grandner said. “In some studies it even beats out depressed mood for being a suicide risk factor.”

Many people turn to medication for relief from insomnia, but better, side effect-free methods are often more successful. Acute insomnia often responds to improvements in sleep hygiene — behaviors such as setting consistent sleep and wake times, limiting caffeine to the morning hours, avoiding naps, and not watching TV in bed.

For people with insomnia disorder, however, the most effective treatment is a form of cognitive behavioral therapy called CBT-I, said Grandner. With the help of a trained therapist, individuals learn to identify and replace the thoughts that keep them from dropping off and address behaviors (such as lying in bed while awake) that perpetuate their sleep difficulties, said Grandner.

Obstructive Sleep Apnea

“One out of every four or five men over the age of 30 have obstructive sleep apnea, and one out of 15 to 20 women of the same age,” said Grandner.

The disorder is basically a mechanical problem. During sleep, muscles around the throat relax, blocking the airway. This causes people to stop breathing for short periods (called apneas) sometimes hundreds of times during the night and often for a minute or longer, leaving them to wake unrested.

“With every apnea, oxygen levels dip and recover, which makes sleep artificially shallow and fragmented,” Grandner said. “That interferes with important processes that happen during sleep, like cellular repair and memory and emotion processing.” Over time, the oxygen deprivation raises the risk for high blood pressure, heart disease, and stroke, because the apneas kickstart the heart when its supposed to be resting, said Grandner.

Oscillating oxygen levels also stress the cells in the kidney, liver, and lungs, said Grandner, putting people with the sleep disorder at risk for renal diseasenon-fatty liver disease, and pulmonary disease.

Continuous positive airway pressure (CPAP) therapy, where a machine attached to a hose and nosepiece deliver a steady flow of air, treats obstructive sleep apnea and has no side effects, said Grandner. “And the machines are more comfortable than they used to be.”

The Connection Between Sleep Disorders, Cell Health, and Aging

Not giving your body enough shuteye is like changing the oil in your car every 5,000 miles rather than the recommended 3,000, said Grandner. Eventually, parts of your car will break down sooner than would have if they were properly maintained.

People with sleep disorders tend to have elevated levels of several hormones, including cortisol, which can promote the development of insulin resistance, a risk factor for life-threatening diseases like obesity and diabetes, Grandner said.

Ongoing sleep loss can also lower the amount of insulin your body produces, and modify glucose transport, which prevents cells from getting the nutrients they need to function optimally, Grandner noted. In fact, research from Pennsylvania State University found insufficient sleep causes levels of ghrelin (the hormone that stimulates appetite and promotes fat storage) to go up and levels of leptin (which regulates body weight by telling the hypothalamus when you’re full) to drop, which may explain why people with sleep disorders are more likely to gain weight and struggle to lose it.

Illness and obesity can shorten your life, but a poverty of sleep also affects aging on the cellular level. UCLA researchers have found that a single night of insufficient sleep can make an older adults' cells age quicker because it activates important biological pathways that promote biological aging. One of those pathways is oxidative stress, a key player in the aging process which is accelerated by lack of sleep, said Grandner.

People who have insomnia also have shorter telomeres, according to recent research in the Journal of Clinical Sleep Medicine. Researchers are still trying to fully understand the link between sleep and telomeres, said Grandner, but it’s clear that when the telomeres that cap off our chromosomes get too short, they’re unable to divide and repair themselves, which accelerates aging.

Sleep loss also leads to the activation of a marker of cellular stress called the unfolded protein response — at least in animal models. “Your DNA creates the RNA which transmits protein, but those proteins are a string of molecules that have to be folded into a very specific shape for the molecule to function properly,” said Grandner. Long-term, protein misfolding is a characteristic of several age-related neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases.

For now, the most important thing to remember about nighttime rest and aging may be this: The effects of a sleep disorder are cumulative. Have a bad relationship with the Sandman in your 20s and 30s and the health effects will pile up. So the sooner you treat sleep issues, the longer — and healthier — your life will be.

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