By Sandee LaMotte, CNN Updated 2:06 PM ET, Wed
April 17, 2019
(CNN)Hey, sleepyheads. What you believe about sleep
may be nothing but a pipe dream.
Many of us have notions about sleep that have
little basis in fact and may even be harmful to our health, according to
researchers at NYU Langone Health's School of Medicine, who conducted a study
published Tuesday in the journal Sleep Health.
"There's such a link between good sleep
and our waking success," said lead study investigator Rebecca Robbins, a
postdoctoral research fellow in the Department of Population Health at NYU
Langone Health. "And yet we often find ourselves debunking myths, whether
it's to news outlets, friends, family or a patient."
Robbins and her colleagues combed through
8,000 websites to discover what we thought we knew about healthy sleep habits
and then presented those beliefs to a hand-picked team of sleep medicine
experts. They determined which were myths and then ranked them by degree of
falsehood and importance to health.
Here are 10 very wrong, unhealthy assumptions
we often make about sleep, an act in which
we spend an estimated third of our lives -- or, if we lived to 100, about
12,227 combined days.
Stop yawning. It's time to put these unsound
sleep myths to bed.
1. Adults need five or
fewer hours of sleep
"If you wanted to have the ability to
function at your best during the day, not to be sick, to be mentally strong, to
be able to have the lifestyle that you would enjoy, how many hours do you have
to sleep?" asked senior study investigator Girardin Jean-Louis, a
professor in the Department of Population Health.
"It turns out a lot of people felt less
than five hours of sleep a night was just fine," he said. "That's the
most problematic assumption we found."
We're supposed to get between seven and 10
hours of sleep each night, depending on our age, but the US Centers for Disease Control and Prevention says
that a third of Americans sleep fewer than seven hours a night. According
to World Sleep Day statistics,
sleep deprivation is threatening the health of up to 45% of the global
population.
"We have extensive evidence to show that
sleeping five hours a night or less, consistently, increases your risk greatly
for adverse health consequences, including cardiovascular disease and early
mortality," Robbins said.
In a longitudinal study of 10,308 British
civil servants published in 2007, researchers found that those who reduced
their sleep from seven to five hours or fewer a night were almost twice as
likely to die from all causes, especially cardiovascular disease.
Science has also linked poor slumber with high
blood pressure, a weakened immune system, weight gain, a lack of libido, mood
swings, paranoia, depression and a higher risk of diabetes, stroke, dementia
and some cancers.
2. It's healthy to be
able to fall asleep 'anywhere, anytime'
Falling asleep as soon as the
car/train/airplane starts moving is not a sign of a well-rested person, sleep
experts say. In fact, it's just the opposite.
"Falling asleep instantly anywhere, anytime,
is a sign that you are not getting enough sleep and you're falling into 'micro
sleeps' or mini-sleep episodes," Robbins said. 'It means your body is so
exhausted that whenever it has a moment, it's going to start to repay its sleep
debt."
You feel sleepy because of a buildup of a
chemical called adenosine in the brain, which happens throughout the day as you
head toward night. Sleeping soundly reduces that chemical so that when you wake
up, the levels are at their lowest, and you feel refreshed.
But the longer you stay awake and the less
sleep you get, the more your adenosine levels rise, creating what's called a
sleep load or sleep debt.
Want to check your level of sleepiness? Look
at the Epworth sleepiness scale,
and if you're worried, check in with a sleep doctor who can do more extensive
testing in a sleep lab.
3. Your brain and body
can adapt to less sleep
People also believed that the brain and body
could adapt and learn to function optimally with less sleep. That too is a
myth, experts say. That's because your body cycles through four distinct phases of sleep to
fully restore itself.
In stage one, you start to lightly sleep, and
you become disengaged from your environment in stage two, where you will spend
most of your total sleep time. Stages three and four contain the deepest, most
restorative sleep and the dreamy state of REM, or rapid eye movement sleep.
"During REM, the brain is highly
reactive," Robbins said. "It almost looks like your brain is awake if
we hook you up to two more electrodes and were able to monitor your brain
waves."
REM can occur any time during the sleep cycle,
but on average, it starts about 90 minutes after you've fallen asleep. REM is
when your body and brain are busy storing memories, regulating mood and
learning. It's also when you dream. Your arm and leg muscles are temporarily
paralyzed during REM sleep, so you can't act out your dreams and injure
yourself.
Because a good night's sleep gives your sleep
cycle time to repeat, you'll go through several REM cycles, which take up about
25% of your total sleeping time.
Another important stage of sleep is deep
sleep, when your brain waves slow into what is called delta waves or slow-wave
sleep. It's the time when human growth hormone is released and memories are
further processed.
"The deeper stages of sleep are really
important for generation of neurons, repairing muscle and restoring the immune
system," Robbins said.
It's tough to wake a person from deep sleep.
If you do wake, you can feel groggy and fatigued; mental performance can be
affected for up to 30 minutes, studies show.
4. Snoring, although
annoying, is mostly harmless
In your dreams, maybe. In fact, "loud,
raucous snores interrupted by pauses in breathing" is a marker for sleep
apnea, a dangerous sleep disorder that, according to the National Heart, Lung and Blood Institute,
increases risk for heart attacks, atrial fibrillation, asthma, high blood
pressure, glaucoma, cancer, diabetes, kidney disease and cognitive and behavior
disorders.
"Sleep apnea is extremely
exhausting," Robbins said. "These patients sleep and then they wake
up over and over; then they are fighting sleep all day long because they're so
exhausted. It's also very underdiagnosed. We believe it affects about 30% of
the population, and around 10% are diagnosed."
5. Drinking alcohol
before bed helps you fall sleep
Do you think a nightcap before bed will help
you fall asleep and stay asleep? Dream on.
Alcohol may help you fall asleep, but that's
where the benefits end, Robbins said. Instead, it traps you in the lighter
stages of sleep and "dramatically reduces the quality of your rest at
night."
"It continues to pull you out of rapid
eye movement and the deeper stages of sleep, causing you to wake up not feeling
restored," Robbins said.
6. Not sleeping? Stay
in bed with eyes closed and try and try
You have to admit, it makes sense: How can you
fall asleep if you're not in the bed trying? Yet sleep experts say that
continuing to count sheep for more than 15 minutes isn't the smartest move.
"If we stay in bed, we'll start to
associate the bed with insomnia," Robbins said. She equates it to
"going to the gym and standing on a treadmill and not doing anything."
In reality, Robbins said, it takes a healthy
sleeper about 15 minutes to fall asleep. If you're tossing and turning much
longer than that, you should get out of bed, change the environment and do
something mindless: "Keep the lights low and fold socks," she
suggested.
Some people also believe that it's just as
refreshing to your body to lie in bed with eyes closed but not sleeping. Nope.
That's another pipe dream, experts say.
7. It doesn't matter
what time of day you sleep
Sleep experts say that's another myth that can
negatively affect your health.
"We recommend that people have a regular
sleep schedule because it controls what we call the biological clock, or
circadian rhythm, of the body," Jean-Louis said. "That controls all
the hormones of the body, body temperature, eating and digestion, and
sleep-wake cycles."
When your inner clock and the outside world
are out of phase, you can feel disoriented, mentally foggy and sleepy at times
when you need to be functioning at optimal levels. Just think of what happens
when you travel across time zones or when daylight savings time kicks in.
Studies of shift workers,
who work unusual hours and live out of sync with their normal
biological rhythm, show that they are at increased risk for heart disease,
ulcers, depression, obesity and certain cancers, as well as a higher rate of
workplace accidents and injuries due to a slower reaction rate and poor
decision-making.
8. Watching TV in bed
helps you relax
Come on, we all do it -- or we check our
laptop or smartphone before we power down for the night. Unfortunately, that
sets us up for a bad night.
"These devices emit bright blue light,
and that blue light is what tells our brain to become alive and alert in the
morning," Robbins explained. "We want to avoid blue light before bed,
from sources like a television or your smartphone, and do things that relax
you."
According to the National Sleep Foundation,
blue light affects the release of melatonin, the sleep hormone, more than any
other wavelength of light. Watching TV or using an electronic device within two
hours of bedtime means it will take you longer to fall asleep, you'll have less
dream state or REM sleep, and even if you do sleep eight or more hours, you'll
wake feeling groggy.
If you or your children can't make that two-hour
cutoff because of homework or late-night work demands, experts suggest dimming
the brightness of the screen or installing an app that can warm the screen to
the sunset colors. Red and yellow have higher wavelengths and don't affect
melatonin.
9. Hitting snooze is
great! No need to get up right away.
Raise your hand if you hit the snooze button.
Why not, right?
"Resist the temptation to snooze, because
unfortunately, your body will go back to sleep -- a very light, low-quality
sleep," Robbins said.
As you near the end of your sleep, your body
is probably nearing the end of its last REM cycle. Hit that snooze button, and
the brain falls right back into a new REM cycle. Now, when the alarm goes off a
few minutes later, you'll be in the middle, not the end, of that cycle, and
you'll wake up groggy and stay that way longer.
Having trouble kicking the snooze button
habit? Put the alarm on the other side of the room, so you have to get out of
bed to turn it off.
And no, you can't tell Google or Alexa to turn
it off. That's cheating.
10. Remembering your
dreams is a sign of good sleep.
"That's a myth, because all of us do
experience dreams four to five times a night," Jean-Louis said. "And
we don't remember because we've not woken up and disrupted our sleep."
A study out of France showed that people
who frequently remember their dreams have higher brain activity in the
information-processing hub of the brains. They also woke twice as often during
the night and were more sensitive to sounds when sleeping and awake.
"Now, I will tell you if you have a dream
with a strong emotional context, it may come back to you at say, two o'clock in
the afternoon, when you have some downtime to relax," Jean-Louis said.
"Sometimes, something would trigger that. But if it is a weird little
mundane dream, most of us who sleep well don't remember those."
More myths
The research team found more myths that we
tend to accept as fact, Jean-Louis said, such as "more sleep is always
better" (no, you really can sleep too much and harm your health),
"taking a nap in the afternoon can fix insomnia" (actually, if you
sleep long enough to enter a REM or deep sleep cycle, it can mess up your body
clock even more), and "it's better to have a warm than cool bedroom"
(no, you sleep better in cooler temps).
Which means that we could all use a bit of
education about good sleep hygiene, a set of habits to form that will set you
up for a lifetime of healthy sleep. The National Sleep Foundation has tips, as does
the CDC.
After all, there's no amount of caffeine that
can help you deal with the adverse implications of insufficient sleep, nor can
you train yourself to adapt to sleep deprivation, Robbins said.
"Sleep is a highly active process,"
she said. "It's crucial, actually, in restoring the body and is in fact
the most efficient, effective way to do so."
Sweet dreams!
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