Three out of four U.S. adults have symptoms of a sleep disorder, such as chronic snoring, difficulty falling or staying asleep, and dozing off during the day, according to a Centers for Disease Control and Prevention survey published in 2021.

“Poor sleep adversely affects health in profound ways,” says Michael Thorpy, M.B.Ch.B., professor in the Saul R. Korey Department of Neurology at Einstein and director of Montefiore’s Sleep-Wake Disorders Center. He points to research showing that sleep deprivation over time can weaken immunity, increase the risk of chronic disease, interfere with concentration and memory, and cause anxiety and depression.

“It’s very clear,” says Dr. Thorpy, “that sleep problems are underdiagnosed and undertreated. The good news is that there’s a growing awareness of the importance of sleep, both in the general population and among clinicians.”

To meet the demand for sleep care, Montefiore’s Sleep-Wake Disorders Center has become an international destination for people whose sleep problems are affecting their quality of life and threatening their health. It has evolved into one of the most comprehensive such programs in the country, with a large patient population and a long waiting list. Work is underway to reconfigure an entire floor of Montefiore’s Westchester Square Campus to accommodate 14 soundproof recording rooms for sleep studies, nearly tripling the current capacity.

The Origins of Sleep Science

Sleep medicine at Montefiore Einstein—and, indeed, the field of sleep medicine in general—owes much to the late Elliot Weitzman, M.D., a former chair of neurology at Einstein. In 1977, Dr. Weitzman created the Montefiore Sleep-Wake Disorders Center, the first such center to be accredited by the group now called the American Academy of Sleep Medicine. 

The biological clock that makes factors such as temperature and hormone secretion rhythmically rise and fall also governs how long and how well we sleep.

In the 1960s, Dr. Weitzman had helped pioneer the field of chronobiology: the study of the circadian (periodic) rhythms, generated by an internal clock in the hypothalamus, that govern the sleep-wake cycle and other processes. He was especially interested in the physiological mechanisms underlying narcolepsy, a disorder that affects the brain’s ability to regulate sleep-wake cycles. Dr. Weitzman’s groundbreaking chronobiology research drew Dr. Thorpy to Einstein.

“I’d become fascinated by Elliot Weitzman’s research on the interaction between sleep and the endocrine system,” says Dr. Thorpy. In 1980, the New Zealand–born neurologist came to Einstein-Montefiore for a fellowship in neuroendocrinology, one of the only such programs in the United States at the time.

By then, Dr. Weitzman had established Montefiore Medical Center’s Laboratory for Human Chronophysiology (LHC), the nation’s first time-isolation laboratory, where he conducted some of the world’s earliest studies showing that sleep and other bodily processes follow cyclic rhythms. Dr. Thorpy recalls his amazement on entering this new world of sleep research.

Carefully screened study participants spent one to six months in windowless apartments with no external cues about time—no clocks, phones, television, radio, or newspapers. Researchers monitored metrics such as temperature and hormone levels throughout the day, with subjects donning electrodes to monitor brain waves during sleep. “What was learned about sleep at the LHC was scientifically quite important,” says Dr. Thorpy.

Contrary to popular belief, for example, the research showed that people cannot consciously control their sleep cycles. Instead, the biological clock that makes physiological factors such as temperature and hormone secretion rhythmically rise and fall also governs how long and how well we sleep. The take-home message, says Dr. Thorpy, is that you can’t abruptly shift your schedule and still expect to get a good night’s rest.

In 1982, when Dr. Weitzman left to establish a chronobiology institute at Cornell University, Dr. Thorpy stepped in to take his place as director of the Sleep-Wake Disorders Center at Montefiore. “The chance to be involved in the early days of sleep medicine was irresistible,” Dr. Thorpy says. He has been here ever since.

Different Sleep Problems for Different People

Other Einstein researchers are investigating sleep difficulties in different age groups and among people historically underrepresented in sleep research. Those Einstein studies include:

• Studies of Hispanics/Latinos. Hispanics/Latinos are the largest minority group in the United States, comprising nearly 20% of the population, but they are underrepresented in research. The Bronx—where more than half the residents are Hispanic/Latino—is an ideal place to address that inequity.

For the past 18 years, Einstein has been one of four U.S. centers participating in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) funded by the National Institutes of Health (NIH). This largest long-term study of Hispanic and Latino health, which began in 2006, has recruited more than 16,000 adults.

A key sleep-related finding from HCHS/SOL pertains to obstructive sleep apnea (OSA), a sleep disorder described below (see “Treating Sleep Problems”). OSA was found to affect 34% of Hispanic/Latino men and 18% of Hispanic/Latina women and is strongly associated with obesity, hypertension, and type 2 diabetes—health problems that are known to disproportionately affect this group. Yet the HCHS/SOL also found that 93% of Hispanic/Latina women and 82% of Hispanic/Latino men with OSA haven’t been treated for the disorder.

“We study this population to see what can be done to improve their health—and sleep is clearly an area where improvements are needed,” says HCHS/SOL co-investigator Yasmin Mossavar-Rahmani, Ph.D., R.D., professor of epidemiology & population health at Einstein. She was also a co-investigator on HCHS/SOL’s “sleep” offshoot: the Sueño Ancillary Study of Latinos’ sleep, which recruited a subset of more than 2,000 HCHS/SOL participants ages 18 to 64 and was conducted between 2010 and 2013.

Over the past decade, researchers have published some 20 papers on results obtained from the Sueño study. Among the findings: Hispanics/Latinos who slept poorly faced an increased risk for developing higher blood pressure and symptoms of depression, and people who didn’t sleep long or well were less likely to eat a nutritious diet. In addition, the Sueño study revealed sleep differences among different ethnic groups. Individuals of Mexican heritage, for example, tended to have longer and less-interrupted sleep compared with the shorter and more-fragmented sleep observed in people of Puerto Rican heritage.

• Sleep Problems in Women. Women tend to report poorer-quality sleep than men and have a higher risk for insomnia. That’s why sleep health was assessed in the NIH-funded Study of Women’s Health Across the Nation (SWAN), a multicenter study designed to examine the health of women during their middle years. Carol Derby, Ph.D., professor in the Saul R. Korey Department of Neurology and in the department of epidemiology & population health at Einstein, is a principal investigator for SWAN and directs its Jersey City, N.J., clinical site.

Sleep for women was widely thought to worsen at midlife, as women go through menopause. In one SWAN study, a subset of 300 women (average age 52 at enrollment) was periodically monitored with wearable sleep devices over a 12-year period. In results described as “surprising,” the study, published in the journal Sleep in April 2020, found that important measures of sleep quality actually improved over time: Sleep duration increased as the women got older, and the amount of time spent awake after sleep onset declined.

“That’s not to say that middle-aged and older women don’t suffer the consequences of poor sleep,” says Dr. Derby, who is also the Louis and Gertrude Feil Faculty Scholar in Neurology at Einstein.

We’re especially interested in seeing if sleep disturbances are a risk factor for dementia, because sleep is something that can be modified.

Carol Derby, Ph.D.

Dr. Derby was involved in a SWAN study examining how the psychological health of older women (average age 65) is influenced by the timing and regularity of sleep within the 24-hour day. Published in 2023 in Sleep Health, it was the first study of its kind to include a diverse group of women.

Based on previous research, the timing of the midpoint for healthy sleep should fall within the 2 a.m. and 4 a.m. “window”: going to bed at 10:30 p.m. and rising at 6:30 a.m., for example, with the midpoint occurring at 2:30 a.m. Compared with women who regularly reached their midpoint of sleep within that window, those who didn’t were much more likely to suffer symptoms of depression, the SWAN study found.

• Sleep and the Aging Brain. Research has linked sleep problems—trouble falling or staying asleep, poor sleep quality, sleeping too little or too much—with increased risk of cognitive decline and dementia. It’s not clear, however, whether sleep problems cause dementia or if brain areas affected by dementia disrupt sleep. The long-running Einstein Aging Study (EAS) is trying to better understand the link between the two. 

Research has linked sleep problems—trouble falling or staying asleep, poor sleep quality, sleeping too little or too much—with increased risk of cognitive decline and dementia.

“We’re especially interested in seeing if sleep disturbances are a risk factor for dementia, because sleep is something that can be modified,” says Dr. Derby. In addition to working on the SWAN study, Dr. Derby is a principal investigator for the EAS, which since 1980 has studied more than 2,500 older Bronx residents, nearly half of whom are Black. “That’s important,” says Dr. Derby, “because where results reveal differences among ethnicities, we’re able to drill down and ask ‘What’s different? What’s driving this?’”

In 2022, Dr. Derby and colleagues began a five-year EAS investigation involving more than 750 Bronx adults. For two weeks each year, the participants wear special digital devices that assess their physical activity, sleep, and blood-sugar levels and their exposure to air pollution. During that same period, they also play brain games five times a day using customized smartphones to test for abilities such as cognitive processing speed and spatial memory (remembering the location of objects or places).  

“We’ll be able to see how last night’s sleep affects tomorrow’s cognition,” Dr. Derby says. “Our hypothesis is that people who are particularly vulnerable to the effects of a poor night’s sleep may be at higher risk for developing cognitive impairment down the road.” If that’s the case, she says, then screening for—and treating—sleep disorders in middle age might help people stay cognitively healthy into their later years.

• Sleep and Children’s Health. Sleep is vital for children’s health, and sleep problems can hamper development of brain regions responsible for memory, intelligence, and well-being and are linked to weight abnormalities and more-frequent illnesses. Even though sleep disorders affect 25% to 50% of children and 40% of adolescents, “those problems are an often-overlooked aspect of child health,” says Karen Bonuck, Ph.D., a professor of family and social medicine, of obstetrics & gynecology and women’s health, and of pediatrics at Einstein. She notes that, in the New York metropolitan area, the Sleep Center at the Children’s Hospital at Montefiore is the only full-service laboratory and evaluation center dedicated to children’s sleep issues.

Childhood sleep problems include lack of sleep and sleep-disordered breathing (SDB), a relatively common condition that refers to snoring and sleep apnea. In a 2014 paper published in the Journal of Pediatrics, Dr. Bonuck reported on findings in which nearly 2,000 children were followed for 15 years. Chronic lack of sleep and sleep-disordered breathing problems each correlated with doubling the likelihood that a child would become obese by age 15.

Dr. Bonuck began studying sleep nearly two decades ago, when she became curious about whether SDB might lead to poor growth in children. After conducting a review of the pertinent scientific literature, Dr. Bonuck and Montefiore Einstein colleagues found good evidence that SDB due to enlarged tonsils and adenoids increases the risk of childhood growth failure. The review, published in 2006 in the International Journal of Pediatric Otorhinolaryngology, noted that “nearly every study finds that otherwise healthy children experiencing growth failure show significant catch-up growth” after surgery for removal of tonsils and adenoids. 

Dr. Bonuck laments that so many teachers, parents, and their children aren’t aware of sleep’s importance. “Research shows that healthy sleep habits—including an early and consistent bedtime routine, limits on screen time, and falling asleep alone—improve how long and well children sleep,” she says. “It’s easier for parents to establish those habits when children are young rather than waiting until they start school or reach adolescence.”

Although so many things are outside of parents’ control, “instilling healthy sleep habits in children is something parents can do that will have a huge positive impact,” says Dr. Bonuck. “Good sleep is a gift you give your child—and it’s free.”

For a 2020 study published in the journal Behavioral Sleep Medicine, Dr. Bonuck and her colleagues interviewed a range of experts to see whether sleep health and sleep problems are being addressed in early-childhood education programs. “They all agreed that sleep education is important, and would like to include it in curriculums,” she says. “But they need help—good resources or a tool kit of some sort. And when we evaluated websites of national organizations dedicated to early-childhood care and education, we found that only half of them offered evidence-based information on sleep. So we clearly need better ways to ‘educate the educators’ about sleep’s importance to children’s health.”

12 Sleep Myths Debunked

In a 2020 study published in the journal Sleep Health, a panel of experts compiled and evaluated 50 “potential myths” about sleep. The 12 below were among those that merited “mythical” status.

Late-night TV watching is more common among short sleepers, according to time-use data from U.S. adults.

1. Being able to fall asleep “anytime, anywhere” is a sign of a healthy sleep system. Excessive daytime sleepiness is a sign of sleep deficiency and a hallmark of obstructive sleep apnea.
2. One night of sleep deprivation will have lasting negative health consequences. Any short-term adverse effects (on cognitive tasks, for example) from a single bad night will likely resolve with recovery sleep.
3. Many adults need only five or fewer hours of sleep for general health. Most adults need seven hours of sleep each night. Consistently sleeping fewer than seven hours a night is linked to a higher risk of heart problems, type 2 diabetes, obesity, and mental health disorders. And don’t expect that staying in bed longer on weekends can make up for lost sleep, Dr. Thorpy advises.
4. Your brain and body can learn to function just as well with less sleep. Research shows that sleep deprivation continues to impair performance, even after weeks of observation.
5. If you can get it, more sleep is always better. Studies have found higher mortality among long sleepers (often defined as those who sleep more than eight hours per night). But it’s also possible that habitual long sleep is a sign of unreported chronic health problems rather than a cause of early mortality.
6. Drinking alcohol before bed will improve your sleep. While it may help you fall asleep faster, a nightcap can cause sleep disturbances, delay rapid eye movement sleep, and worsen sleep apnea.
7. In terms of your health, it does not matter what time of day you sleep. Night-shift workers get less sleep as well as lower-quality sleep than day workers and are at higher risk for depression, type 2 diabetes, and breast cancer.
8. Lying in bed with your eyes closed is almost as good as sleeping. The two are quite different metabolically. For example, brain activity during sleep takes on a much different pattern compared with activity in the awake brain.
9. If you have difficulty falling asleep, it is best to stay in bed and try to fall back to sleep. To improve your ability to fall asleep and your overall sleep quality, engage instead in “stimulus control therapy”: leave your bed, avoid blue light, and return to bed only when you’re tired.
10. Watching television in bed is a good way to relax before sleep. Time-use data from U.S. adults finds that late-night TV watching is more common among short sleepers. (In one U.S. survey, half of all respondents reported watching TV in the 30-minute period before bedtime.)
11. Exercising within four hours of bedtime will disturb your sleep. For most people, nighttime exercise doesn’t interfere with sleep.
12. An afternoon nap can compensate for poor nighttime sleep. Although siestas are a way of life for some people, experts recommend that people who have trouble sleeping at night should avoid napping during the day.

Treating Sleep Problems

Do you struggle to get to sleep or stay asleep? Snore or wake up gasping for breath? What about more-subtle problems, such as having difficulty concentrating or chronically feeling tired, depressed, or irritable? A sleep-medicine specialist may be able to help.

Chronic insomnia—difficulty sleeping three or more nights weekly for three months or longer—is one of the most common sleep disorders.

Clinicians who aren’t well-versed in sleep disorders may not connect these symptoms to sleep problems, Dr. Thorpy says. “For most patients, help is definitely available, and it can make a huge difference in your overall health and quality of life. It’s important to keep pursuing help if you aren’t finding good answers.”

We talked with Dr. Thorpy and colleagues about advances in treating the three major sleep conditions diagnosed at the Montefiore Sleep-Wake Disorders Center.

1. Narcolepsy. The Sleep-Wake Disorders Center has a special interest in hypersomnia disorders, which cause people to be excessively sleepy during the day or to sleep longer than usual at night. Clinical staff have garnered an international reputation for diagnosing and treating difficult cases.
   
   One of the most common hypersomnias is narcolepsy, a neurological disorder that causes bouts of extreme sleepiness and muscle weakness during the day. People with narcolepsy may feel rested upon waking but then suffer attacks of extreme sleepiness and muscle weakness. While falling asleep or waking up, people with narcolepsy may experience sleep paralysis, which prevents them from moving for up to 15 minutes and is often accompanied by hallucinations. “Narcolepsy is a devastating disorder that makes it hard for patients to participate fully in life,” says Dr. Thorpy.
   
   The Sleep-Wake Disorders Center participated in clinical trials evaluating oxybate (Xyrem, Lumryz, and the lower-sodium version, Xywav), now considered the first-line therapy for narcolepsy. The drug improves the quality of nighttime sleep, reduces episodes of daytime sleepiness, and prevents cataplexy—a feature of narcolepsy in which strong emotions such as laughter, anger, or fear cause people to lose control of their muscles and fall limp for periods ranging from a few seconds to a few minutes.
   “Oxybate has been a real game-changer for narcolepsy patients,” says Dr. Thorpy. But Xyrem and Xywav are rapidly metabolized, requiring patients to wake up during the night for a second dose. In May 2023, the U.S. Food and Drug Administration approved an extended-release form of sodium oxybate called Lumryz, which can be taken just once at bedtime. “This long-awaited therapy will make life so much easier for patients and help restore the natural sleep-wake cycle,” says Dr. Thorpy.
   
    
2. Insomnia. Chronic insomnia—difficulty sleeping three or more nights weekly for three months or longer—is one of the most common sleep disorders. In clinical guidelines issued in 2021, the American Academy of Sleep Medicine strongly recommends cognitive behavioral therapy for chronic insomnia (CBT-I) as the first-line treatment for the disorder. 
   
   “The evidence shows that CBT-I works much better than sleep medications, and without their side effects,” says Usman Riaz, M.D., an assistant professor of psychiatry and behavioral sciences at Einstein and a Montefiore psychiatrist who specializes in addiction therapy and sleep medicine. “By restructuring patients’ thoughts and helping them make behavioral changes that address the underlying insomnia, CBT-I helps resolve insomnia, and improvements from the therapy can usually be maintained over the long term.” 
   
   The cognitive aspect of CBT-I teaches patients to ferret out and replace false notions that interfere with their ability to sleep—for example, that they don’t sleep at all, or that they must sleep for a set number of hours nightly. “Small improvements count, and setbacks happen,” Dr. Riaz says. “It’s important not to engage in ‘all or none’ thinking.” 
   
   The behavioral component helps people create an environment conducive to good sleep and retrain their brains to associate being in bed with sleeping. This involves, for example, reserving the bed only for sleep and sexual activity—no phones, television, or music—and, if you’ve been lying awake for 20 minutes, going to another room and sitting quietly until you’re bored and sleepy enough to go back to bed. Following those techniques can reestablish the association between the bed and sleep.
   
   For motivated patients, this approach to better sleep typically works well and quickly, says Dr. Riaz, who notes that “most people on average need only four or five sessions of CBT to realize significant improvement in their sleep.” 
   
    
3. Obstructive Sleep Apnea. In OSA, throat muscles frequently relax during sleep, blocking the windpipe and causing people to stop breathing for up to a minute at a time. A survival mechanism rouses sleep-apnea sufferers just enough to allow them to gasp for air, resulting in snoring—the sound of air forced through a partially obstructed throat. An estimated 30 million Americans have sleep apnea, but only 6 million have been diagnosed with the condition, according to the American Academy of Sleep Medicine.
   
   The gold standard for diagnosing OSA is polysomnography—a sleep study performed while a person is asleep. An alternative is physician-prescribed home tests, which have made apnea diagnoses easier and more cost-efficient for patients. Each test kit includes a fingertip oxygen monitor, a mask, and sensors to measure the rise and fall of the abdomen and chest to track breathing and oxygen levels. Dr. Thorpy says home tests are a good option for people suspected of having milder apnea and those whose main complaint is snoring and who don’t have other health issues.
   
   A common treatment for OSA is use of a continuous positive airway pressure (CPAP) machine. By delivering a steady stream of air down the windpipe, these devices prevent the airway collapse that causes OSA. Excess body weight puts pressure on the upper airways and is strongly associated with OSA. “Patients who lose a significant amount of weight may be able to reduce the air pressure required from their treatment devices or even stop using them altogether,” says Dr. Thorpy.

One Man’s Sleep Apnea Journey

Sixteen years ago, when he was in his 40s, John Jones (not his real name) found himself in a daily battle with utter exhaustion. He struggled to stay alert in his work as an accountant. When he was at home, fatigue sapped his patience with his three young daughters. His wife complained about his nighttime restlessness and relentless snoring. But what concerned him most was the danger of falling asleep at the wheel during the long commute from his home in Poughkeepsie, N.Y., to his office in Tarrytown.

“It became my routine to stop at one or two gas stations when I felt groggy driving in,” he says. “And coming home, I often had to park midway and take a nap.”

On the recommendation of his primary care doctor, Mr. Jones saw a sleep-medicine specialist. An overnight sleep study revealed that a common sleep disorder, OSA, was interfering with his sleep and causing his constant fatigue.

Mr. Jones was wise to seek help. Apnea’s interrupted breathing does more than disrupt sleep. The drop-off in oxygen intake taxes the heart muscle, increasing the risk of heart attack and heart failure as well as stroke. Left untreated, sleep apnea also slows metabolism and raises blood-glucose levels, leading to weight gain and type 2 diabetes.

Mr. Jones’s sleep doctor prescribed a CPAP machine, which uses mild air pressure to keep airways open during sleep. “The first night I used it, I woke up refreshed and not lethargic, feeling better than I had in ages,” he says. “It was like night and day.”

There were other beneficial changes as well. His blood pressure, which had started climbing before his sleep apnea was treated, fell to normal levels, and he was calmer and functioned better. “Even my vision was better,” he says with a laugh. “Your brain just doesn’t work well without rest.”

Recently, Mr. Jones’s sleep problems returned. He tried taking the prescription sleep drug zolpidem (Ambien), but it left him too groggy to drive safely. This time, he consulted with Dr. Thorpy and spent a night at the Montefiore Sleep-Wake Disorders Center. After Dr. Thorpy adjusted the settings on his CPAP machine, Mr. Jones immediately felt like himself again.

In retrospect, he thinks his late father, who developed heart problems and needed a pacemaker, probably suffered from undiagnosed sleep apnea. “In the summer we slept with the windows open at our house in the Bronx,” he recalls. “You could hear Dad snoring all the way down the block. I wish we’d known that snoring was a symptom of a serious but treatable disorder.”