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Why you can’t sleep — and how to deal

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While Mozart, Thomas Edison and other greats claimed to sleep just four hours per night, insomnia is miserable — and lost sleep can harm our health. Learn from UCSF sleep researchers Ying-Hui Fu, Ph.D., Andrew Krystal, M.D., Aric Prather, Ph.D. and Louis Ptáček, M.D., about why many people have trouble sleeping, plus the healthy sleep habits you can count on for relief and popular myths to watch out for.

5 reasons you can’t sleep

Unfortunately, the science of sleep is complicated and there’s no one-size-fits-all answer. But here are common causes for lack of sleep.

1. You literally can’t breathe

The first possible cause to consider is sleep apnea: You are choking on your own collapsing airway, awakening over and over again, just enough to gasp for air, sometimes as often as once every minute. Although sleep apnea affects 22 million Americans, most people don’t recognize it in themselves and only seek treatment at the ultimatum of their miserable bed partner, whose endurance of nightly snoring, gasping, and choking sounds ensures their own variety of sleep deprivation. (No bed partner? Other warning signs include excessive daytime sleepiness and morning headaches.)

The good news: Once sleep apnea is diagnosed, treatments for it — lifestyle changes, oral appliances, and airway pressure devices — are very effective.

2. You are anxious or distressed

Almost everyone has at least occasionally experienced the maddening exhaustion of wanting, needing, begging to fall asleep, but being stuck wide awake instead, mind racing. This is insomnia — which can show up as an inability to fall asleep or to stay asleep, or both — and it is often triggered by anxiety or psychological distress.

What’s going on? Basically, your nervous system is stuck in fight-or-flight mode, and the hormones cortisol, adrenaline, and noradrenaline keep your brain alert and ruminating. About 25% of Americans will suffer a short-term bout of insomnia in any given year, but it usually resolves on its own. For about a quarter of this group, however, the problem becomes chronic, lasting three months or longer. At that point, it’s definitely time to see a sleep specialist. (The best treatment for insomnia usually isn’t a pill.)

3. Your body’s clock is out of sync

There are countless ways to confuse your circadian rhythms. Hop a flight halfway around the world and you’ll wake up before sunrise and be a staggering zombie by midafternoon. Stay up night after night, doom-scrolling or playing email catch-up, and you’ll find your regular bedtime is hard to get back to. Switch between day and night shifts, and you may find yourself snapping at loved ones, blanking out while driving, or rereading a sentence several times over, unable to focus.  

Many of the sleep disorder patients Krystal sees have an out-of-sync rhythm called delayed sleep phase syndrome; they tend to stay up late and sleep late. There’s nothing inherently wrong with a late bedtime, but since the world doesn’t stop for late sleepers, this pattern generally leads to the terrible outcomes associated with too little sleep. “The goal in these cases is to fix the circadian rhythm problem,” Krystal says, “because you can’t drag a person to go to sleep at a time that their biology is not aligned with.”

4. We live in an always-on culture

Even those of us who don’t suffer from sleep apnea, insomnia, or sleep-phase disorders often don’t get the sleep we need. As UC Berkeley neuroscientist Matthew Walker, Ph.D., puts it in his New York Times bestseller, Why We Sleep, “Humans are not sleeping the way nature intended. The number of sleep bouts, the duration of sleep, and when sleep occurs [have] all been comprehensively distorted by modernity.”

Ptáček puts it in these stark terms: “Right now, awareness of the impact of sleep deprivation is where we were with smoking 40 years ago. Back then, the tobacco industry fought to obscure the risks of cigarettes. Today, our entire society is fighting against sleep health, through this 24/7 culture we live in.” 

5. Your genes play a role

Super-sleepers inherit a preternatural ability to thrive on only a few hours of sleep. But this genetic trait is very, very rare, so if you regularly sleep less than 7½ hours a night and suspect you might fall into this category, think again; chances are much higher that you are not only sleep-deprived but also so used to living this way you can’t even see the problem. It’s true, however, that there’s much more variation in individuals’ sleep needs than we generally recognize. “A lot of people say everyone must sleep 7½ to 8½ hours or you’re not going to be healthy. That’s not true,” says Ptáček. “There are some people who require less, and some who require more.”

What’s more, genetics can account for extreme night owls (who might naturally sleep, for example, from 2 to 10 a.m.) and extreme morning larks (who might sleep from 8 p.m. to 4 a.m.). But unlike treatable circadian rhythm disorders, these patterns are inherited and lifelong. For anyone with these atypical sleep traits, obligations as simple as helping kids with after-dinner homework or showing up for morning classes or meetings can be serious problems. 

Better-sleep myths — what not to do

Healthy sleep habits are pretty straightforward: Keep a consistent wake-up time. Exercise. Avoid caffeine, alcohol and big meals right before bed. Cultivate a cool, dark bedroom and banish devices. Make time to wind down before bed. It’s easy to find these and other good habits online, but UCSF’s sleep experts warn that you may also find some common tips that you should take with a grain of salt: 

Don’t: Force yourself into a consistent bedtime

A regular bedtime is great if you’re sleeping well. But if you can’t fall asleep, trying to force it will only make things worse. Instead, get up and do something relaxing until you’re sleepy. Lying awake perpetuates insomnia by stoking your anxiety and weakening your mind’s association that bed means sleep.   

Don’t: Obsess over sleep data from your smart devices

Aric Prather says today’s sleep trackers can’t accurately estimate sleep stages, but the analyses they generate may cause sleep anxiety. There’s actually a term for this: orthosomnia. Most people are better off just listening to their bodies and waking at a consistent time. “You know when you wake up and don’t feel refreshed,” says Prather. “You don’t need a device to tell you that.”  

Don’t: Focus too much on blue light 

Worried about the effect of your smartphone’s blue light on your sleep? Some evidence suggests that blue light exposure can impair sleep, but Prather says the hype may be stronger than the science. Likely more harmful to slumber are some kinds of content. Reading a relaxing book on your phone is probably fine. But the stimulation of emailing, texting, tweeting or doom-scrolling the news could trigger insomnia. Even so, it wouldn’t hurt to turn on your phone’s blue-light filter.

Don’t: Misunderstand melatonin  

Melatonin is one of the most commonly used supplements, and one of the most misunderstood. Melatonin does not make you sleepy. Your brain produces melatonin in response to darkness as part of your body’s internal clock. So, melatonin supplements can help reset your circadian clock after a trans-Atlantic flight or some other disruption. But they are not the key to calming your racing thoughts. 

Get the full scoop on current sleep science from UCSF Magazine

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