How to Sleep Better
The Science of Sleep
Sleep is one of the strangest things we do each day. The average adult will spend 36 percent of his or her life asleep. For one-third of our time on earth, we transition from the vibrant, thoughtful, active organisms we are during the day and power down into a quiet state of hibernation.
But what is sleep, exactly? Why is it so important and so restorative for our bodies and minds? How does it impact our lives when we are awake?
The Purpose of Sleep
Sleep serves multiple purposes that are essential to your brain and body. Let's break down some of the most important ones.
Every day, your brain accumulates metabolic waste as it goes about its normal neural activities. While this is completely normal, too much accumulation of these waste products has been linked to neurological disorders such as Alzheimer's disease.
Alright, so how do we get rid of metabolic waste? has suggested that sleep plays a crucial role in cleaning out the brain each night. While these toxins be flushed out during waking hours, researchers have found that clearance during sleep is as much as than during waking hours.
The way this process occurs is fairly remarkable:
During sleep, brain cells actually shrink by 60 percent, allowing the brain's waste-removal system—called the glymphatic system—to essentially “take out the trash” more easily. The result? Your brain is restored during sleep, and you wake up refreshed and with a clear mind.
Sleep is crucial for , which is the process that maintains and strengthens your long-term memories. Insufficient or fragmented sleep can hamper your ability to form both concrete memories (facts and figures) and emotional memories.
have shown that when you sleep 5.5 hours per night instead of 8.5 hours per night, a lower proportion of the energy you burn comes from fat, while more comes from carbohydrate and protein. This can predispose you to fat gain and muscle loss. Additionally, insufficient sleep or abnormal sleep cycles can lead to insulin insensitivity and , increasing your risk of diabetes and heart disease.
All of this to say, that better sleep is critical for your mental and physical health. Before we get too deep into this sleep guide though, let's pause for just a second. If you're enjoying this article on sleep, then you'll probably find my other writing on performance and human behavior useful. Each week, I share self-improvement tips based on proven scientific research through my free email newsletter.
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How Much Sleep Do You Need?
Alright, so sleep is important, but how much sleep do you really need? To answer that question, let's consider an experiment conducted by researchers at the University of Pennsylvania and Washington State University.
The researchers began the experiment by gathering 48 healthy men and women who had been averaging seven to eight hours of sleep per night. Then, they split these subjects into four groups. The first group had to stay up for 3 days straight without sleeping. The second group slept for 4 hours per night. The third group slept for 6 hours per night. And the fourth group slept for 8 hours per night. In these final three groups—4, 6, and 8 hours of sleep—the subjects were held to these sleep patterns for two weeks straight. Throughout the experiment the subjects were tested on their physical and mental performance.
Here's what happened…
The subjects who were allowed a full 8 hours of sleep displayed no cognitive decreases, attention lapses, or motor skill declines during the 14-day study. Meanwhile, the groups who received 4 hours and 6 hours of sleep steadily declined with each passing day. The four-hour group performed worst, but the six-hour group didn't fare much better. In particular, there were two notable findings.
In the words of the researchers, sleep debt “has a neurobiological cost which accumulates over time.” After one week, 25 percent of the six-hour group was falling asleep at random times throughout the day. After two weeks, the six-hour group had performance deficits that were the same as if they had stayed up for two days straight. Let me repeat that: if you get 6 hours of sleep per night for two weeks straight, your mental and physical performance declines to the same level as if you had stayed awake for 48 hours straight.
When participants graded themselves, they believed that their performance declined for a few days and then tapered off. In reality, they were continuing to get worse with each day. In other words, we are poor judges of our own performance decreases even as we are going through them.
The Cost of Sleep Deprivation
The irony of it all is that many of us are suffering from sleep deprivation so that we can work more, but the drop in performance ruins any potential benefits of working additional hours.
In the United States alone, studies have estimated that sleep deprivation is costing businesses over $100 billion each year in lost efficiency and performance.
As Gregory Belenky, Director of the Sleep and Performance Research Center at Washington State University, puts it: “Unless you’re doing work that doesn’t require much thought, you are trading time awake at the expense of performance.”
And this brings us to the important question: At what point does sleep debt start accumulating? When do performance declines start adding up? According to a wide range of studies, the tipping point is usually around the 7 or 7.5 hour mark. Generally speaking, experts agree that 95 percent of adults need to sleep 7 to 9 hours each night to function optimally. Most adults should be aiming for eight hours per night. Children, teenagers, and older adults typically need even more.
The Theory of Cumulative Stress
Imagine that your health and energy are a bucket of water. In your day-to-day life, there are things that fill your bucket up. Sleep is one of the main inputs. These are also things like nutrition, meditation, stretching, laughter, and other forms of recovery.
There are also forces that drain the water from your bucket. These are outputs like lifting weights or running, stress from work or school, relationship problems, or other forms of stress and anxiety.
The forces that drain your bucket aren't all negative, of course. To live a productive life, it can be important to have some of those things flowing out of your bucket. Working hard in the gym, at school, or at the office allows you to produce something of value. But even positive outputs are still and they drain your energy accordingly.
These outputs are cumulative. Even a little leak can result in significant water loss over time.
How Sleep Works
The Sleep-Wake Cycle
The quality of your sleep is determined by a process called the sleep-wake cycle.
There are two important parts of the sleep-wake cycle:
1. Slow wave sleep (also known as deep sleep)
2. REM sleep (REM stands for Rapid Eye Movement)
During slow wave sleep the body relaxes, breathing becomes more regular, blood pressure falls, and the brain becomes less responsive to external stimuli, which makes it more difficult to wake up. This phase is critical for renewal and repair of the body. During slow wave sleep, the pituitary gland releases growth hormone, which stimulates tissue growth and muscle repair. Researchers also believe that the body's immune system is repaired during this stage. Slow wave sleep is particularly critical if you're an athlete. You'll often hear about professional athletes like Roger Federer or LeBron James sleeping 11 or 12 hours per night.
As one example of the impact of sleep on physical performance, consider a study researchers conducted on the Stanford basketball players. During this study, the players slept for ten hours per night (compared to their typical eight hours). During five weeks of extended sleep, the researchers measured the basketball players accuracy and speed compared to their previous levels. Free throw shooting percentage increased by 9 percent. Three point shooting percentage increased by 9.2 percent. And the players were 0.6 seconds faster when sprinting 80 meters. If you place heavy physical demands on your body, slow wave sleep is what helps you recover.
REM sleep is to the mind what slow wave sleep is to the body. The brain is relatively quiet during most sleep phases, but during REM your brain comes to life. REM sleep is when your brain dreams and re-organizes information. During this phase your brain clears out irrelevant information, boosts your memory by connecting the experiences of the last 24 hours to your previous experiences, and facilitates learning and neural growth. Your body temperature rises, your blood pressure increases, and your heart rate speeds up. Despite all of this activity, your body hardly moves. Typically, the REM phase occurs in short bursts about 3 to 5 times per night.
Without the slow wave sleep and REM sleep phases, the body literally starts to die. If you starve yourself of sleep, you can't recover physically, your immune system weakens, and your brain becomes foggy. Or, as the researchers put it, sleep deprived individuals experience increased risk of viral infections, weight gain, diabetes, high blood pressure, heart disease, mental illness, and mortality.
To summarize: slow wave sleep helps you recover physically while REM sleep helps you recover mentally. The amount of time you spend in these phases tends to decrease with age, which means the quality of your sleep and your body's ability to recover also decrease with age.
When Should I Go to Sleep?
If you're getting the recommended 8 hours of sleep, does it matter when you get it?
“The time of night when you sleep makes a significant difference in terms of the structure and quality of your sleep,” said Dr. Matt Walker, head of the Sleep and Neuroimaging Lab at the University of California, Berkeley.
The ratio of REM to non-REM sleep changes through the night, with non-REM sleep dominating cycles earlier in the night and REM sleep kicking in closer to sunrise, Walker said. That means a late night could result in insufficient amounts of deep, non-REM sleep. As we discussed earlier, it's crucially important to get healthy amounts of both REM and non-REM sleep.
So how early do you need to be to bed to get enough of each type of sleep? Walker says there's a window of several hours, about 8 p.m. to midnight.
The best time for though, will vary.
Till Roenneberg, a professor of chronobiology at Ludwig-Maximilian University in Munich who studies the biological roots of sleep, says each person has a unique internal timing profile called a sleep chronotype that determines where on the scale from “early bird” to “night owl” we fall. Your chronotype is largely genetic.
When choosing your bedtime, try not to fight your physiology. The best bedtime will differ a little bit for everyone, but it's crucial that you pay close attention to your internal clock and what your body is telling you. As long as you're getting the recommended 8 hours of sleep, just focus on finding the time that works best for you.
How to Sleep Better
How to Fall Asleep Fast
The light from computer screens, televisions, and phones can hinder the production of melatonin, which means your body isn't preparing the hormones it needs to enter the sleep phase. Specifically, it is the blue wavelength of light that seems to decrease melatonin production. Developing a “power down” routine where you shut off all electronics an hour or two before sleep can be a big help. Additionally, working late at night can keep your mind racing and your stress levels high, which also prevents the body from calming down for sleep. Turn off the screens and read a book instead. It's the perfect way to learn something useful and power down before bed. (Another option is to download an app called , which reduces the brightness of your screen closer to bedtime.)
Researchers believe that at least 50 percent of insomnia cases are emotion or stress related. Find outlets to reduce your stress and you'll often find that better sleep comes as a result. Proven methods include daily journaling, deep breathing exercises, meditation, exercise, and keeping a gratitude journal (write down something you are thankful for each day).
Daily Habits for Better Sleep
Next, let's talk about how to sleep better by harnessing the power of a few simple, daily habits.
Aim for at least 30 minutes of sun exposure each day.
When it gets dark outside, dim the lights in your house and reduce blue or full-spectrum light in your environment. , a free software app for your computer, makes the color of your computer's display adapt to the time of day, warm at night and like sunlight during the day.
If you're having trouble falling asleep, eliminating caffeine from your diet is a quick win. If you can't go without your morning cup of coffee, then a good rule of thumb to keep in mind is “No coffee after noon.” This gives caffeine enough time to wear off before bed time.
Tobacco use has been linked to a long line of health issues, and poor sleep is another one on the list. I don't have any personal experience with tobacco use, but I have heard from friends who have quit successfully that book is the best resource on the topic.
Is your bedroom designed to promote good sleep? The ideal sleeping environment is dark, cool, and quiet. Don't make your bedroom a multi-purpose room. Eliminate TVs, laptops, electronics, and clutter. These are simple ways to of your bedroom, so that sleep is easier and distraction is harder. When you go to the bedroom, go there to sleep.
Natural Sleep Aids
There are too many benefits to exercise to list them all here. When it comes to sleep, exercise will make it easier for your brain and body to power down at night. Furthermore, obesity can wreak havoc on your sleep patterns. The role of exercise only becomes more important with age. Fit middle-aged adults sleep significantly better than their overweight peers. One caveat: avoid exercising two to three hours before bedtime as the mental and physical stimulation can leave your nervous system feeling wired and make it difficult to calm down at night.
Most people sleep best in a cool room. The ideal range is usually between 65 to 70 degrees Fahrenheit (18 to 21 degrees Celsius).
A quiet space is key for good sleep. If peace and quiet is hard to come by, try controlling the bedroom noise by creating “white noise” with a fan. Or, use ear plugs.
This one is a slippery slope. It is true that having a drink before bed — a “night cap” — often does help people fall asleep. However, while it makes it easier to fall asleep, it actually reduces the quality of your sleep and delays the REM cycle. So you fall asleep faster, but it's possible that you'll wake up without feeling rested. It's probably best to improve your sleep through other methods before resorting to alcohol to do the job.
Final Thoughts on How to Sleep Better
Cumulative sleep debt is a barrier between you and optimal performance. If you want to know how to sleep better, the answer is simple but remarkably underrated in our productivity-obsessed culture: get more sleep.
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