Sleep is tainted with misinformation, and it’s driving up sleep anxiety. We dove into deep research on sleep and discovered the surprising truth about six common myths.

Why it matters: Evolution programmed us to all sleep differently (it was a survival mechanism). Understanding the nuances of sleep can help you figure out what’s good and bad about your sleep habits. The result: you’ll rest easier.

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Six Sleep Myths

In brief

A lack of sleep leads to all kinds of physical and mental health problems. But as we’ve realized how important sleep is, we’ve begun making all sorts of hyper-specific recommendations around it. Many of those recommendations, however, are wrong—and doing more harm than good.

The details

If humans don’t sleep enough, we turn into unhealthy, insane idiots.

Consider the curious case of Randy Gardner. In 1963, Gardner was 17 and needed a high school science fair project. So he decided to see how long he could go without sleeping.

Word got out. And once he’d made it three days without sleep, a scientist from Stanford named William Dement saw an opportunity. Dement observed Gardner for what became the longest period a human has ever gone without sleeping: 11 days and 24 minutes.

Of course, Gardner paid for it. By day four, his concentration and short-term memory plummeted. For example, Dement would give Gardner mental tasks, like subtracting from 100. But Gardner would stop midway through.

When asked why he stopped, Gardner couldn’t remember that he’d even started. “It was almost like an early Alzheimer’s thing brought on by a lack of sleep,” Gardner told NPR.

Along the way, he became paranoid and began hallucinating. He went from a gregarious, outgoing teen to straight dickish. “The longer I stayed awake, the more irritable I got,” said Gardner. “I had a very short fuse. I was a brat.”

Other research suggests his body paid the price. Lack of sleep is associated with all kinds of poor health outcomes.

• People who get less than five hours a night have a higher risk of heart attacks, cancer, diabetes, and weight gain.
• This is why, for example, heart attack incidents in the U.S. rise 25 percent the day after we lose an hour of sleep to daylight savings time.

But as we’ve learned how vital sleep is to keep humans physically and mentally well, we’ve begun to push sleep into the common trap we do with all good behaviors. We started making hyper-specific recommendations around it.

Suppose you were to ask someone about sleep and sleeping better. They’d probably fire off a series of rules perfect sleep requires: you must sleep a certain amount of time at a certain temperature inside a room designed to mimic a black hole.

• But sleep doesn’t follow rules. Like all of biology, it falls into ranges. Your sleep is your sleep. It’s individual. What works for one person may not work for another.
• This means cut-and-dried rules around sleep often leave people high and dry. Or anxious that they’re doing something wrong, leading them to make all sorts of changes and purchases to fix a problem that may not exist.

So let’s dive into six big sleep myths.

Wednesday’s post will reveal a guide to help you figure out if you’re sleeping enough and some tactics to help you sleep better if you think you’re lacking.

Myth 1: Eight hours of sleep is best

In brief

There’s no strong evidence that eight hours is best. Most people sleep seven hours and, in fact, sleeping 7-ish nightly hours was associated with the lowest risk of death.

The details

Eight hours a night is the oldest myth in the book.

Researchers in the Anthropology department at Harvard analyzed a range of studies on this. Their takeaway: “Most adult Westerners probably average about seven hours a night, a good hour (13 percent) less than the eight hours we supposedly need.”

And the amount of sleep the average person gets changes depending on their age and the season. For example, Westerners sleep an average of 6.5 hours in the summer and 7.5 hours in the winter.

Of course, many Westerners are unhealthy. So you might think our lack of health is due to getting less than eight hours. People often point out that our sleep is disturbed by technology like TVs, smartphones, alarm clocks, etc.

But in 2015, scientists at UCLA put sleep trackers on people from three different pre-industrial tribes from Tanzania, Namibia, and Bolivia. None of these tribes have electricity or smartphones, and all three of these tribes don’t seem to get the chronic diseases that kill most Westerners, like heart disease.

The scientists assumed that without electronics keeping them awake, the tribe members would sleep eight solid hours. And that would be one explanation for their great metabolic health.

Nope. They found the tribe members averaged between 5.7 and 7.1 hours a night. That’s less than us. Like us, they slept less in the warm summer months (5.7 to 6.5 hours/night) and more in the winter months (6.6 to 7.1 hours/night).

Scientists first realized that eight hours was probably a myth in 2002. That’s when researchers analyzed health and sleep data from one million Americans. They found that people who slept eight hours had 12 percent higher death rates than people who slept 6.5 to 7. The study was controversial since the sleep data was self-reported.

But the research has been piling up ever since. It suggests people who sleep seven-ish hours a night have the lowest risk of all-cause mortality. What’s more, it actually seems bad to get more than eight hours.

As the same Harvard anthropologists put it:

“(Westerners) who sleep about seven hours tend to live longer than those who sleep more or less. In no study is eight hours optimal, and in most of the studies people who got more than seven hours had shorter life spans than those who got less than seven hours (an unresolved issue, however, is whether it would be beneficial for long sleepers to reduce their sleep time.)”

If you regularly sleep eight or even nine hours, don’t freak out. The are many factors at play here. The point is, rather, eight hours isn’t magic. Wednesday’s post will reveal a questionnaire that’ll help you figure out if your sleep times are working for you.

Myth 2: Light and sound will ruin your sleep

In short

Some people sleep better in darkness and silence. Others benefit from some light and noise, like having a TV on in the background. If early humans couldn’t sleep without disturbances, we would have never slept.

The details

I spent some time in the Bolivian Amazon with one of the tribes in that UCLA study for my forthcoming book, Scarcity Brain.

They put me up in a thatched hut, and I slept on a small “bed” of elevated boards. I could see light through the stick walls—a campfire in the distance, the moon showing brightly on the surrounding jungle. And the noise was, well … babies crying, dogs barking, bugs buzzing, people talking, birds squawking, the jungle emitting a wall of jungle sounds.

It was chaos. But this sort of bedtime bedlam has likely been the norm throughout history. Us modern people—with our blacked-out, temperature-controlled, near-silent rooms, and plush beds—are probably the weird ones.

That’s the conclusion of Carol Worthman, anyway. She’s one of the great anthropologists of our time and the world’s foremost expert studying how different cultures sleep and how humans likely slept across our evolution. Her takeaways:

• Sleep has been a dangerous activity throughout most of history. It’s when we’re most vulnerable to predators.
• To avoid danger, humans would sleep together around a fire. The light from the fire and sound of others talking, babies crying, and more may actually signal to our brain that it is safe to fall asleep.

Still today, some noise and light help many people nod off. Consider my wife. She likes to fall asleep with the TV on—it helps her sleep better. This makes sense, given Worthman’s findings.

Worthman also shows that people can adapt to sleeping in light and sound. If we couldn’t sleep at all with sound around us, even some loud sounds, densely packed cities wouldn’t exist.

Obviously you can’t have an air raid siren going off and a strobe light in front of your face all night.

But the lesson here is to figure out what environment you sleep best in. Experiment—and don’t try to force darkness and silence if it’s not helping you.

Myth 3: Sleeping pills will help you

In short

Research suggests sleeping pills work by placebo and have clear health harms. One scientist believes we’ll eventually view prescription sleeping pills like we do cigarettes.

The details

As far back as the 1970s, a researcher named Daniel Kripke noticed that people who took sleeping pills had a greater mortality rate than those who didn’t. But it was a chicken and egg problem. Was their lack of sleep hurting them, or was it the pills?

Kripke has been looking into prescription sleeping pills ever since. In a massive 2010 study, he found taking sleeping pills “was associated with greater than threefold increased hazards of death … in 2010, hypnotics may have been associated with 320,000 to 507,000 excess deaths in the USA alone.”

The study was observational; the researcher didn’t say sleeping pills directly caused these deaths. But he did write, “The consistency of our estimates across a spectrum of health and disease suggests that the mortality effect of (sleeping pills) was substantial. Even 10,000 yearly excess deaths caused by hypnotics would be too many.”

Funny enough, sleeping pills seem to work mainly by placebo effect. That’s according to a 2012 study. It found that people prescribed the pills slept the same length as those prescribed a sugar pill.

When asked why he didn’t do a more stringent randomized controlled trial of sleeping pills, Kripe wrote, “Perhaps for reasons similar to the absence of randomized trials of cigarettes and of skydiving without parachutes.”

One sleep researcher at UCLA thinks we’ll eventually view prescription sleeping pills like we do cigarettes.

If you’re an insomniac who currently takes Ambien, Sonata, or Lunesta, Wednesday’s post will cover an approach that many sleep scientists believe works better and safer.

Myth 4: We sleep to rest our bodies

In short

Sleep restores your brain more than your body. Getting a bad night’s sleep hurts some but not all types of athletic performance.

The details

Obviously sleep does rest our bodies, but so does, say, laying on the couch and watching Top Chef. There isn’t strong research suggesting that muscle repair after a big workout is vastly more powerful during sleep versus lounging.

Scientists from Stanford found that a bad night’s sleep can hurt athletic performance. But it depends on what kind of performance. Activities with a strong mental component are hurt most.

For example, bad sleep doesn’t impair strength because lifting is often a quick, semi-mindless act. Bad sleep does seem to impact accuracy and lead endurance athletes to tap out earlier (this is probably because elite endurance sports are more of a mental than a physical game at the higher levels).

Let’s return to Gardner, the teenager who stayed up for 11+ days. He said, “Physically, I didn’t have any problems. Not walking or throwing the basketball around or playing the pinball games. But the mental part is what went downhill.”

And so, as the Harvard scientist Daniel Lieberman wrote, “It doesn’t take a lot of brainpower to realize that sleep is mostly about the brain.”

There seem to be two ways sleep helps our brain.

1. Sleep helps us learn and remember important things. When we’re awake, our memories seem to go into a sort of short-term bank. Then, when we’re in certain stages of sleep, our brain culls through these memories. It puts the most important memories in long-term storage and deletes the useless ones.
2. Sleep “cleans” our brain. The brain is like an engine that does a lot of work during the day. Engines emit smog—in the case of the brain, this smog is called “metabolites.”

But because our brain is tightly sealed off, it can’t seem to get rid of these metabolites as it’s up and running while we’re awake.

Picture this like a car running at idle in a garage. But pretend the car’s engine can’t run with the garage door open. So across the day, the engine runs in the closed garage, and smog builds and builds in the brain. Run the engine too long with the garage door closed, and you get a dangerous smog buildup.

As we sleep, it’s like the engine shuts off and the garage door opens. During certain sleep phases, some areas of our brain expand by 60 percent, which allows the previous day’s metabolites to clear. This also lets in enzymes that repair and rejuvenate receptors in the brain. Sort of like having a mechanic come in to tune the engine while the garage is open and the engine is “off.”

The researchers at Harvard wrote, “For every hour spent awake storing memories and amassing waste, we need approximately fifteen minutes asleep to process those memories and clean up.” Like all specific numbers, the researchers note, it’s an average. Some people need more than fifteen minutes, others less, depending on age.

Myth 5: Waking up in the middle of the night is bad

In short

Many of us seem “programmed” to wake at night. And that’s OK! What’s bad is worrying when you wake up in the middle of the night. That anxiety over lost sleep can impact your ability to fall back asleep.

The details

Carol Worthman, the anthropologist who studies sleep patterns across cultures, has also discovered that throughout history, it’s been common for different societies to have two phases of sleep. Basically: many people wake up in the middle of the night and chat or even work for an hour or so, then go back to sleep.

Many Westerners, as well as different pre-industrial populations, do this. Importantly, these people don’t seem to be any worse off than people who sleep uninterrupted.

We all have our own sleep patterns, and a 2017 study suggests a very good reason for this.

A researcher from the University of Toronto and one of my friends and colleagues at UNLV, Alyssa Crittenden, tracked the sleeping habits of 33 Hadza hunter-gatherers for 20 days. They found that there were only 18 minutes when all 33 people were asleep simultaneously. That’s not 18 minutes in one night—that’s 18 minutes across 20 nights.

On average, there were usually about eight tribe members awake at any given point in the night.

This is a normal and beneficial phenomenon. Here’s why we evolved to all have different sleep habits:

• When humans evolved from apes, we stopped living and sleeping in trees and started living and sleeping on the ground.
• But the ground is much more dangerous—especially when we’re asleep. It’s where lions, hyenas, and snakes skulk around, looking for something to sneak up on and kill.
• For safety, it’s necessary to always have at least one person awake and keeping watch. So evolution essentially mashed up our sleeping patterns, altering them as we age, so we’d always have someone awake and on watch. Scientists call this “the sentinel hypothesis.”

Another sleep researcher told the BBC that these mid-night wake-ups may have also given us a relaxing time to destress and meditate on our dreams and emotions.

Hence, we all still sleep differently.

The problem with giving hyper-specific rules around sleep is that it can cause anxiety. “Many people wake up at night and panic (that they’ve woken up),” a neuroscientist at Oxford told the BBC. “I tell them they are experiencing a throwback to the bi-modal sleep pattern.”

Myth 6: You must time your sleep cycles to leverage REM sleep

In short

REM sleep still perplexes sleep scientists. We don’t have enough evidence to suggest that trying to time and alter our sleep cycles with sleep devices helps at a population level. (But please continue this if you’re doing it and it helps you.)

The details

You may have heard you should time your REM sleep cycles.

This appears largely to be a theory invented by people who don’t study sleep. When the world’s top sleep researchers recently met at a conference, they called REM sleep “the proverbial riddle wrapped in a mystery inside an enigma.”

If humans couldn’t function unless our sleep cycles were perfectly timed, we’d have all died off.

Imagine that it’s 200,000 years ago, and we’re asleep. We’re only 47 minutes into our final 90-minute sleep cycle. But then we get woken up by a tiger who has come into our camp because it’s craving human flesh.

If we couldn’t perform well no matter what point in our sleep cycle we’d woken up, we’d die.

Timing sleep cycles seems to be one more way the rise of hyper-specific health recommendations makes our lives more finicky and anxious rather than better.

If you’re doing this and it helps you, please continue. But do make sure the practice doesn’t become a liability. People who practice specific routines often fall apart when their routine doesn’t go perfectly. Being resilient to change makes you a more versatile and effective human.

There are more myths out there. But those six seem to be the most common.

Thanks for reading this post, which started as something small and grew and grew.

Have fun, don’t die.

-Michael

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