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.
The first
purpose of sleep is restoration. 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? Recent research has
suggested that sleep plays a crucial role in cleaning out the brain each night.
While these toxins can be
flushed out during waking hours, researchers have found that clearance during
sleep is as much as two-fold faster 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.
The second
purpose of sleep is memory consolidation. Sleep
is crucial for memory consolidation,
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.
Finally, sleep
is paramount for metabolic health. Studies 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 metabolic syndrome,
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.
First, sleep
debt is a cumulative issue. 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.
Second,
participants didn't notice their own performance declines. 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 outputs 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 at least 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 you, 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
Develop a
“power down” ritual before bed. 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 f.lux,
which reduces the brightness of your screen closer to bedtime.)
Use relaxation
techniques. 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.
Get
outside. Aim for at least 30 minutes of sun exposure each
day.
Turn out the
lights. When it gets dark outside, dim the lights in your
house and reduce blue or full-spectrum light in your environment. F.lux, 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.
Avoid caffeine. 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.
Stop smoking or
chewing tobacco. 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 Allen Carr's
Easy Way to Stop Smoking book is the best
resource on the topic.
Use the bedroom
for sleep and sex only. 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 improve
the choice architecture 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
Exercise. 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.
Temperature. Most
people sleep best in a cool room. The ideal range is usually between 65 to 70
degrees Fahrenheit (18 to 21 degrees Celsius).
Sound. 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.
Alcohol. 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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Credits
The
article was posted by JAMES CLEAR,
Original title: The Science of Sleep: A Brief Guide on How to Sleep
Better Every Night
