Insomnia at the Pinnacle of Power

We don’t hear much about the sleep of presidents and prime ministers except for the hours they get: President Obama, 6; George W. Bush, 8: Margaret Thatcher, 4. Their personal habits matter little compared with the decisions they make and the work they do in office.

But Dr. Li Zhisui wrote about insomnia at length in his biography of Mao Zedong, The Private Life of Chairman Mao, suggesting that our leaders’ sleep (or sleeplessness) may affect their decisions and behavior more than we think.

Insomnia was a problem for Mao ZedongWe don’t hear much about the sleep of presidents and prime ministers except for the hours they get: President Obama, 6; George W. Bush, 8: Margaret Thatcher, 4. Their personal habits matter little compared with the decisions they make and the work they do in office.

But Dr. Li Zhisui wrote about insomnia at length in his biography of Mao Zedong, The Private Life of Chairman Mao, suggesting that our leaders’ sleep (or sleeplessness) may affect their decisions and behavior more than we think.

Mao’s Stress-Related Insomnia

As Mao’s personal physician, Li was expected to give up all other duties to see to the chairman’s health and wellbeing. So he worked and lived in the ruler’s compound, observing him at close range and eventually becoming Mao’s confidant.

Li noted right away that Mao’s sleep was erratic. Anticipatory anxiety would keep him awake on nights before public events where he was to address the masses.

“Often he would get no sleep at all the night before the festivities,” Li wrote. “He was exhilarated by the crowds and their adulation, and his energy always carried him through the event, but he often caught cold afterward. Sometimes the cold would become bronchitis, and he would be miserable for weeks.”

A Possible Circadian Rhythm Disorder

But Li observed that Mao’s erratic sleep patterns seemed to be driven by internal as well as external factors. Mao was a night owl who tended to be awake when most other people were sleeping.

“His body refused to be set to the 24-hour day,” Li wrote. “He stayed awake longer than others, and much of his activity took place at night. If he went to bed one day at midnight, the next night he might not sleep until 3 in the morning, and the day after that he would not sleep until 6. His waking hours grew longer and longer until he would stay awake for 24, or even 36 or 48, hours at a stretch. Then he could sleep 10 or 12 hours continuously, and no amount of noise or commotion would wake him.”

This erratic sleep pattern would probably be classified as a circadian rhythm disorder today. It might be delayed sleep phase disorder, a diagnosis often given to night owls who prefer to be up at night and sleep in late in the morning. It might also be non-24-hour sleep-wake disorder, a problem often seen in people who are blind, who cannot detect daylight and whose body clocks—as a result—are not set to the 24-hour day.

Whatever the diagnosis, the problem may have been amplified by Mao’s unusual lifestyle. He spent most of his time indoors—in his bedroom, according to Li, where thick dark curtains blocked out the sunlight. Without exposure to sunlight, his circadian rhythms may have become desynchronized, a situation that could easily give rise to insomnia.

But Li felt Mao’s problem was partly organic, and that he’d simply been born with a wayward body clock predisposed to run on its own time.

Insomnia Affected Mao’s Behavior

People with sleep problems like Mao’s don’t usually have easy lives. Perennial lateness and poor performance interfere with relationships and jobs.

But Mao rose to a leadership position despite his strange sleep habits and, as Chairman of the Communist Party, he called the shots. Without regard for the sleep needs of his associates, he would call impromptu staff meetings at 3 a.m. On the spur of the moment he would order his whole staff to get up early to prepare for a 4 a.m. departure by train.

As disruptive as his strange sleep habits were to others, they were a source of great anxiety to Mao himself, Li said. Mao tried swimming, dancing, and walking to wear himself out, and he took up to 4 times the recommended dosage of powerful sleeping pills. But often, Li said, nothing worked.

Could there be a relationship between the tight-fisted control Mao insisted on exerting over his country and the lack of control he seemingly had over his sleep? What do you think?

Are We Really Sleep Deprived?

People with insomnia typically worry about not getting enough sleep. It’s easy to understand why. The media are are full of stories warning of the perils of insufficient sleep: obesity, diabetes, dementia, cardiovascular disease.

But a study of sleep in 3 traditional societies published in October suggests that humans may need less sleep than we think we do—which should give insomniacs food for thought.

Insomniacs may not need as much sleep as they thinkPeople with insomnia typically worry about not getting enough sleep. It’s easy to understand why. The media are full of stories warning of the perils of insufficient sleep: obesity, diabetes, dementia, cardiovascular disease.

The Centers for Disease Control and Prevention for several years declared insufficient sleep to be a public health epidemic (last year they revised the language to “public health problem”). And according to an estimate set forth in Sleepless in America, a documentary released on the National Geographic Channel in December 2014, Americans sleep considerably less than we did 150 years ago.

But a study of sleep in 3 traditional societies published in October suggests that humans may need less sleep than we think we do—which should give insomniacs food for thought.

Making Inferences About Sleep in Times Past

How did people sleep millennia ago? Has electric lighting really had as negative an impact on sleep as sleep experts claim it has?

The scientists and anthropologists who conducted this study couldn’t travel back in time to assess the sleep of our ancestors. So they did the next best thing: study the sleep of 3 hunter–gatherer and hunter–horticultural societies in existence today. These traditional peoples, who live without electricity or any modern technology, live in equatorial regions of Tanzania, Namibia, and Bolivia.

What They Found Out

The investigators used wristwatch-type devices to measure sleep duration and light exposure for 94 adults over a total of 1,165 days. Following are some interesting findings:

  • People in these traditional cultures slept 5.7 to 7.1 hours a night—less than average sleepers in modern industrialized societies like the United States. Yet extensive research has found that although their daily energy expenditure is about equal to that of most Americans, they’re healthier and more physically fit than we are.
  • People did not go to sleep at sunset, as has been assumed about people before the advent of artificial lighting. On average, they went to sleep 3.3 hours after sunset, keeping vigil in the dark except for a small fire and moonlight. So electric lighting is probably not the only reason we like to stay up to watch the late show. Perhaps Thomas Edison did not have as big an impact on sleep as we think.
  • People got their sleep in a single sleep episode uninterrupted by long periods of wakefulness. Daytime naps were the exception rather than the rule. This challenges the idea that early humans had two separate sleep episodes interrupted by a wakeful period in the middle of the night, or that they routinely took daytime siestas.

Relevance to Insomnia

Many people with insomnia say they need 8 hours of sleep a night, and maybe some of us do. Yet although this study by itself is not evidence that we need any less, if it convinced us to revise our beliefs about sleep need downwards, it wouldn’t be a bad thing.

Sleep therapists say that one thing that happens to many insomniacs as their sleep improves is that they let go of the idea that 8 is the magic number. Sleep quality may matter more than the number of hours we get.

Why Such Alarmist Messages?

Sleep isn’t always seen as important—yet it is a pillar of health alongside diet and exercise. But the alarmist tone of some of the messages we hear about not getting enough sleep (“a public health epidemic”), and the fact that healthy sleep is almost always defined as a certain number of hours, is worrisome to people with insomnia and others whose nightly share of shut-eye falls short. How helpful are such messages really?

The cynic in me says the pharmaceutical companies and medical device makers are behind this campaign to insist that we aren’t getting the sleep we need. Because who stands to gain more from convincing us that we’re sleep deprived than the folks who sell Ambien and CPAP machines?

But Americans toward the end of the 19th century were also worried about their sleep. After the Civil War, many were moving off the farm and into the city, where life was more stimulating, and both faster paced and more sedentary, than on the farm. A widely held view was that civilization was evolving faster than the human organism could keep pace with, and good sleep was falling by the wayside.

Are we living in a similar climate today? Do the dire warnings about insufficient sleep fit in with general concerns about the pace of our 24/7 lives, and do they likewise reflect anxiety about social changes and/or fear that we can’t keep up?

I’d like to know what you think.

Eat Right to Sleep Tight

In the late Renaissance, many medical authorities were convinced that digestive processes controlled the duration of sleep. People slept as long as necessary to digest their evening meal.

That proposition fell by the wayside long ago—yet new evidence suggests that the timing of meals does affect our sleep. Particularly in people who are prone to insomnia, eating more regular meals, and eating dinner earlier in the evening, may be important keys to sounder sleep and good health.

Eating irregular meals, and iron-high snacks at night, is harmful to sleep and healthIn the late Renaissance, many medical authorities were convinced that digestive processes controlled the duration of sleep. People slept as long as necessary to digest their evening meal.

That proposition fell by the wayside long ago—yet new evidence suggests that the timing of meals does affect our sleep. Particularly in people prone to insomnia, eating regular meals, and eating dinner earlier in the evening, may be important keys to sounder sleep and good health.

In Sync

Regularity is a familiar theme to people with insomnia. “Go to bed and get up at the same time every day,” we hear again and again.

Good sleepers tend to do this naturally. Their stable, high quality sleep is a sign that their internal circadian rhythms are all synched up. These rhythms are established by the body clock, which hews to a 24-hour cycle with daily exposure to sunlight.

People with insomnia are not so regular about sleep. Over a two-week period, the authors of a study of daily activities and sleep found, insomnia subjects had over an hour of daily variability in when they went to bed and got up in the morning. This variability could throw their internal rhythms out of whack and lead to symptoms of insomnia.

But compared with normal sleepers, the insomniacs were also more variable in when they had meals and snacks. For them, lunch could vary by as many as 3 hours from one day to the next. The timing of their evening snacks had a range of almost 3 hours as well.

A Relationship between Eating and Sleeping         

Sunlight is not the only thing that keeps our circadian rhythms synched up. In addition to the master clock in the brain, which is set by the sun, many peripheral clocks are spread throughout our bodies. Some of them are sensitive to the timing of meals. Eating at odd hours disrupts their rhythm. Circadian rhythms are then thrown out of sync, and this invites insomnia.

“This finding highlights the potential importance of regular mealtimes,” the authors state. “Perhaps incorporating a regular meal schedule into treatment for those with insomnia could help to align the internal clock with a 24-hour light/dark cycle, which would contribute to healthier sleep.”

Avoid Iron-Rich Foods at Night

Another study suggests that eating foods high in iron at night is harmful to health. Not only does it alter circadian rhythms, but it may also increase our vulnerability to obesity, diabetes and other metabolic disorders.

This study was conducted on mice. One of the many peripheral clocks in mice and humans is located in the liver, an organ that regulates blood glucose levels. In this study, scientists found that dietary iron establishes the circadian rhythm of the liver.

Eating iron-rich foods during the daytime is healthy. Metabolic processes that ensue after a meal high in meat, beans, leafy green vegetables or dried fruit are not harmful when they occur in sync with the body’s natural rhythms.

But feeding iron to mice at a time when they would normally be asleep resulted in the clock in the liver going out of sync with the body clock in the brain, and a dysregulation of blood glucose levels. Particularly in shift workers, said investigators in ScienceDaily, eating foods high in iron at night could lead to obesity, diabetes and other metabolic disorders.

So if you’re a poor sleeper or prone to raiding the fridge at midnight, aim for regular meals and lighter midnight snacks.

What foods do you typically eat when you can’t sleep?

 

Six Misconceptions about Sleep and Insomnia

Most of us know that drinking coffee after dinner will probably disrupt our sleep and that regular exercise will improve it. But some ideas I see tossed out about sleep and insomnia are not quite accurate. Here are six misconceptions followed by information that is evidence based.

insomnia | many people have beliefs and attitudes about sleep that are not factualMost of us know that drinking coffee after dinner will probably disrupt our sleep and that regular exercise will improve it. But some ideas I see tossed out about sleep and insomnia are not quite accurate. Here are six misconceptions followed by information that is evidence based. Find sources by clicking the links in the blog.

Insomnia mainly has to do with a lack of REM sleep (when most dreaming occurs).

Overall, studies comparing people with insomnia to normal sleepers show that insomnia is associated with reductions in both deep sleep and REM sleep. Deep sleep enables the consolidation of memories for factual information and events, and persistent insomnia tends to interfere with this process. Shortened REM sleep, on the other hand, leads to alterations in the processing of emotion—another symptom of insomnia.

The fact that I don’t remember my dreams means I don’t get enough REM sleep.

No evidence shows that sufficient REM sleep is tied to the remembering of dreams. What does seem to be true is that people who remember dreams typically wake up more often during REM sleep than people who don’t remember dreams. But these awakenings are so brief that the dreamer may not be aware of them.

I need several hours of deep sleep to function well.

Young children spend about a third of the night in deep sleep. But the amount of deep sleep humans get declines dramatically during adolescence. The average middle-aged adult spends about 15 percent of the night in deep sleep, and older adults may get as little as 10 percent. As critical as deep sleep is to our ability to function, it accounts for a small percent of the total sleep we get. Our descents into deep sleep occur mostly in the first part of the night.

Rates of insomnia are highest among people in high-status, high-stress jobs.

Stress has a huge impact on sleep, and high stress reactivity may be a defining characteristic of people who develop insomnia. But all else equal, people who earn large salaries are not the ones most likely to toss and turn at night. People of low socioeconomic status with lower education levels are more vulnerable to insomnia than surgeons and CEOs.

Waking up for a stretch in the middle of the night is a sign that something is wrong with my sleep.

Not necessarily. Historical evidence suggests that until the widespread use of electric lighting, this segmented sleep pattern was not unusual. People went to bed soon after nightfall and woke up later to make love, tend to animals and crops, or simply lie awake with their minds adrift. Then they went back to sleep for the rest of the night.

Being awake in the middle of the night may be inconvenient, and with strategic use of light and sleep compression you may be able to whittle that wakefulness down. But if you’re functioning OK in the daytime, being awake at night does not signal something amiss.

If my sleep is lousy, I should make a point of going to bed earlier.

If you have insomnia, going to bed early will likely make the problem worse. The arousal system is fully engaged in the hours leading up to bedtime, early research has shown: most people have a hard time falling asleep in the evening. Here’s a better rule of thumb: If your sleep is lousy, make a point of staying up until you feel sleepy. Only then should you go to bed.

Questions or doubts about sleep or insomnia? Share them here, and I’ll do my best to respond and clarify.

Go Paleo for Better Sleep

Occasionally I hear from an insomnia sufferer who can tell me precisely the times she woke up the previous night. “Went to sleep at 11:30, up again at 12:55. Lay awake for an hour. Got back to sleep but woke up again to go to the bathroom at 2:40. Woke up again at 4:40 and stayed awake until the alarm rang at 6. What should I do?”

This person—let’s call her Judith—doesn’t sound like she’s getting much sleep: little more than 4 hours if you tally up the numbers. Few of us could thrive on a steady diet of 4-hour nights, and Judith is no exception. She works full time and cares for her family in the evening. When the alarm rings, she’s got to be up and on her toes all day until she crashes at 10 p.m. No wonder she has a lot of anxiety about sleep and is desperate for more of it.

I’ve blogged about various ways to improve sleep, but one small change of habit I’ve mentioned deserves more attention.

Flintstone-napOccasionally I hear from an insomnia sufferer who can tell me precisely the times she woke up the previous night. “Went to sleep at 11:30, up again at 12:55. Lay awake for an hour. Got back to sleep but woke up again to go to the bathroom at 2:40. Woke up again at 4:40 and stayed awake until the alarm rang at 6. What should I do?”

This person—let’s call her Judith—doesn’t sound like she’s getting much sleep: little more than 4 hours if you tally up the numbers. Few of us could thrive on a steady diet of 4-hour nights, and Judith is no exception. She works full time and cares for her family in the evening. When the alarm rings, she’s got to be up and on her toes all day until she crashes at 10 p.m. No wonder she has a lot of anxiety about sleep and is desperate for more of it.

I’ve blogged about various ways to improve sleep, but one small change of habit I’ve mentioned (Clocking the Hours at Night) deserves more attention.

You’ve Heard of the Paleo Diet?

I’d like to propose that all of us who worry about not getting enough sleep adopt a more Paleolithic approach to the night.

I’m not suggesting we should sleep communally or in caves or anything like that. I don’t assume our distant ancestors experienced less stress and anxiety and therefore slept better than we do. They didn’t have jobs or mortgages to worry about . . . but they were mincemeat if they didn’t worry about predators and human enemies at night. The idea that they slept more peacefully than we do is probably a myth.

“In the ancient world,” says Eluned Summers-Bremner, author of Insomnia: A Cultural History, “sleep was by no means an event to which individuals felt they were entitled, or, like hunting for food, one that was always easily achieved.”

Yet one thing our Paleo forebears almost certainly did not worry as much about was time: time enough to do everything that needed to be done during the day, and time enough to sleep at night. Back then, the concept of time as measurable except through natural phenomena—the alternation of daylight and darkness, the waxing and waning of the moon, the changing of the seasons—likely did not exist. People worked as long as needed to complete a task and they slept when they felt sleepy. End of story.

Moving Forward in History

But time began to be measured in hours and minutes, and associated with work and money, with the introduction of the clock in the merchant economy that arose in Europe in the fourteenth century, Summers-Bremner says. The Late Middle Ages is when mention of time- and work-related sleeplessness began to crop up in works of literature: something resembling our experience of insomnia today.

We Can’t Go Back

We can’t actually approach the night with the mindset of a Fred Flintstone. When we think of time we think of a clock ticking away, constantly moving forward by minutes and hours. And every passing second shrinks our sleep opportunity down.

But if we can’t adopt a Paleo mindset with respect to time, at least we can take care to avoid staring time in the face. We may not be able to turn back the clock, but at night we can turn our clocks to the wall.

Resisting the urge to glance at the clock may not be as easy for every insomnia sufferer as it sounds. But take it from one who’s been there: it cuts down on anxiety about sleep.

Do you watch the clock at night? Do you think it affects your sleep in any way?

Insomnia: Let’s Stop Blaming the Victim

It’s cruel to blame people for health problems they have little if anything to do with creating. Yet the urge to do so is powerful when the true causes of an affliction remain unknown. In the 20th century many illnesses were seen as psychological or behavioral problems, and insomnia was one.

We’re in the 21st century now, and biology and neuroscience are teaching us that the causes of many chronic disorders and serious diseases are complex. But some people still regard insomnia as stemming from “bad” behavior or as “all in the head.” Here’s my take.

BlamingIt’s cruel to blame people for health problems they have little if anything to do with creating. Yet the urge to do so is powerful when the true causes of an affliction remain unknown. In the 20th century many illnesses were seen as psychological or behavioral problems.

Cancer? A disease of people who repressed their emotions. All that pent-up emotion and hostility just had to find expression some way, and it did so by causing cells to run amok.

AIDS? Brought on by sexual promiscuity.

Narcolepsy? Before the recent discovery of orexins–neurotransmitters that help keep us awake and which are lacking in narcoleptics, making them prone to daytime sleep attacks—narcolepsy was explained as a psychological problem of people who lacked motivation.

Insomnia? It, too, was self-created. “You! Are really the major cause of your own insomnia,” declared self-help author Valerie Moolman in 1968, at a time when sleeplessness was blamed on everything from internalized emotion and a desire for attention to bad habits like worrying and staying out late.

We’ve Come a Long Way, Baby . . . or Have We?

We’re in the 21st century now–century of the brain. Biology and neuroscience are teaching us that the causes of many chronic disorders and serious diseases are complex.

But wait. Near the end of journalist David K. Randall’s new book, Dreamland, Randall states this: “And yet insomnia is a unique and difficult condition to treat because it is self-inflicted.” Self-inflicted? Aren’t we beyond holding people responsible for a sleep disorder most sleep researchers say is based in part upon vulnerabilities predisposed at birth?

I don’t think we’ve come that far yet. “I have been made to feel like I must be doing something wrong,” wrote Carol, an insomnia sufferer who reviewed my book, The Savvy Insomniac, just last month, “drinking too much coffee (1 cup in the morning) or not really trying to get to sleep.”

“Bad” Behavior

There are some things we can do that will probably interfere with sleep:

  • Drinking coffee later in the afternoon or in the evening
  • Drinking alcohol right before bed
  • Sleeping late in the morning or taking long naps.

Avoiding these behaviors will likely improve sleep. But many of us already know these things and take them to heart. We hew pretty close to the straight and narrow . . . and still we have trouble sleeping.

Do We Create Insomnia in Our Heads?

Believing we can’t sleep will make sleep more difficult. Fearing insomnia will, too. Yet we don’t develop such beliefs and fears of our own volition. We learn them unconsciously. (See my blog on fear of insomnia.) And once in place, they’re hard to dislodge. (But not impossible. See my blog on laying fear of sleeplessness to rest.)

Even researchers who theorize that chronic insomnia develops in people who think too much about sleep or try too hard to do it are retreating from this claim as more evidence comes in suggesting the underlying cause of insomnia to be excessive arousal of the central nervous system.

Changing habits and mindsets can go a long way toward helping insomniacs sleep. But it’s time we stopped pointing fingers at the sleepless and started looking at insomnia as the multifactorial sleep disorder it truly is.

Off-Label Meds for Insomnia

Post-marketing tests now show that Ambien and Lunesta, the most popular sleeping pills today, are not as benign as they once were believed to be. Are we moving into a period similar to that which occurred in the 1980s, when physicians moved away from prescribing sleeping pills for people with insomnia and prescribed off-label medications instead?

dont-knowIn 1999, during a terrible bout of insomnia, I went to see a sleep specialist. A friend had told me that Klonopin (a.k.a. clonazepam) got rid of her insomnia and convinced me that I should try it myself. What was there to lose?

“Klonopin!” the doctor exclaimed at my suggestion. “That’s an antipsychotic.” (Clonazepam is now more often classified as an antianxiety medication.) “Your symptoms don’t warrant that. Take Ambien as needed, and don’t worry about taking a second pill if you wake up in the middle of the night.”

Fast forward to last month, when I went in to my primary care doctor for a routine physical and asked for a refill of Ambien, which I take occasionally.

“I’m not sure about the Ambien,” the doctor said. “It’s a bad drug. There’s a new story about it coming out everyday. How about trying clonazepam instead? I didn’t use to prescribe anything at all to patients with sleep problems. But now I’ve got patients using clonazepam daily and I’m not seeing any harmful effects.”

Déjà Vu

I’m reminded of events that occurred in the early 1980s, when the then-popular sleeping pill Halcion made its dramatic fall from grace. Higher dosages of the drug came to be associated with depression, suicidal thoughts, and violent behavior, and Upjohn, the drug’s maker, was accused of withholding information about these side effects from the FDA. So powerful was this sleeping pill believed to be that a handful of Americans were actually absolved of murder when their lawyers used what came to be known as “the Halcion defense” in court. (“The drug made me do it.”)

One result was that many doctors stopped prescribing sleeping pills for people with insomnia and started prescribing antidepressants like trazodone and amitriptyline instead. These antidepressants had not been tested and found to be effective for insomnia. But they were known to have sedating properties and believed to be safer than sleeping pills (never mind side effects like daytime fogginess, cardiovascular complications and erectile dysfunction in men). Did they work and were they tolerable? Insomniacs I interviewed for my book gave very mixed reviews.

History Repeats Itself

Post-marketing tests now show that Ambien and Lunesta, the most popular sleeping pills today, are not as benign as they once were believed to be. (See my blogs about Ambien for details.)

Now I hear of people taking drugs like clonazepam and Seroquel (quetiapine), an atypical antipsychotic, for help with sleep. These drugs have not been approved for the treatment of insomnia, but testimonials suggest that doctors are prescribing them, and insomniacs writing on Drugs.com give them fairly high marks (9.1 out of 10 and 8.3 out of 10, respectively).

I don’t have a problem with doctors prescribing medications off label if there’s hard evidence that they work. But where is that evidence? In Pubmed I can’t find a single study assessing the safety and efficacy of clonazepam for insomnia. The few tests assessing the efficacy of quetiapine are inconclusive, according to a meta-analysis published in 2012. Another meta-analysis concludes that safety concerns outweigh benefits.

Does it make sense to replace sleeping pills with known benefits and side effects with drugs whose efficacy and safety for insomnia is untested?

This is not a rhetorical question. I’d like to hear your thoughts.

The Rich Sleep Better (They Haven’t Always)

So it’s news that the rich sleep better in Canada (as headlines in various online publications recently proclaimed)? Not exactly shocking. Who wouldn’t sleep better owning a Mercedes than a rickety Ford?

Insomnia is more often the curse of those who struggle to make mortgage payments and pay for healthcare than the well to do.

rich-man2So it’s news that the rich sleep better in Canada (as headlines in various online publications recently proclaimed)? Not exactly shocking. Who wouldn’t sleep better owning a Mercedes than a rickety Ford? Insomnia is more often the curse of those who struggle to make mortgage payments and pay for healthcare than the well to do.

If today this feels like a no-brainer, people saw things differently in the past. “The sleep of a laboring man is sweet, whether he eat little or much,” the Bible says, “but the abundance of the rich will not suffer him to sleep.”

In Shakespeare’s day, too, insomnia was understood to be an affliction of the wealthy and the powerful rather than the lower classes. “Not all these, laid in bed majestical/Can sleep so soundly as the wretched slave/who with a body filled and vacant mind/Gets him to rest,” says King Henry.

What other factors make us susceptible to sleep problems?

Young vs. Old

Being older has always been associated with sleeping poorly, and with good reason. Seniors take longer to fall asleep, experience less deep sleep (the restorative stuff) and less REM sleep (when we dream), and wake up more often during the night. Their sleep cycle shifts to earlier hours. These changes may have to do with altered patterns of neuronal activity in the brain, as well as other health problems that occur more frequently with age.

Male vs. Female

Being female, too, makes people more vulnerable to persistent insomnia. Three women have trouble sleeping for every 2 men. Hormonal changes during the menstrual cycle, and in perimenopause and menopause, tend to interfere with sleep, as do hormonal and physical changes during pregnancy. The increased risk may also have to do with roles women play and related mental health problems. Women often serve as primary caretakers in the family and are more likely to suffer from depression and anxiety.

But early medical treatises make no mention of insomnia as a female problem. Near the end of the fifteenth century, Italian philosopher Marsilio Ficino regarded “long bouts of sleeplessness” as a problem of the intellectual, who by definition was male. Too much study and agitation of the mind was the cause of sleeplessness and melancholia, he said.

White vs. Nonwhite

That race might factor into susceptibility to insomnia was never put to the test until recently. Yet it turns out to be true. Researchers at the University of Pennsylvania concluded that “perceived discrimination remains a significant predictor of sleep disturbance.” We’re also more vulnerable to insomnia if we’re single or without children.

None of these factors alone or combined determine how well we’ll sleep. But biology and circumstance combine to make it likely that some of us will toss and turn and others, sleep like logs.