By
Camille Peri
WebMD Feature
WebMD Feature
Reviewed
by James Beckerman, MD, FACC
You know
lack of sleep
can make you grumpy and foggy. You may not know what it can do to your sex life, memory,
health, looks, and even ability to lose weight.
Here are 10 surprising -- and serious -- effects of sleep
loss.
Sleep
deprivation was a factor in some of the biggest disasters in recent
history: the 1979 nuclear accident at Three Mile Island, the massive Exxon
Valdez oil spill, the 1986 nuclear meltdown at Chernobyl, and others.
But sleep
loss is also a big public safety hazard every day on the road. Drowsiness can
slow reaction time as much as driving drunk. The National Highway Traffic
Safety Administration estimates that fatigue
is a cause in 100,000 auto crashes and 1,550 crash-related deaths a year in the
U.S. The problem is greatest among people under 25 years old.
Studies
show that sleep loss and poor-quality sleep also lead to accidents and injuries
on the job. In one study, workers who complained about excessive daytime
sleepiness had significantly more work accidents, particularly repeated work
accidents. They also had more sick days per accident.
Sleep
plays a critical role in thinking and learning. Lack of sleep hurts these
cognitive processes in many ways. First, it impairs attention, alertness,
concentration, reasoning, and problem solving. This makes it more difficult to
learn efficiently.
Second,
during the night, various sleep cycles play a role in “consolidating” memories
in the mind. If you don’t get enough sleep, you won’t be able to remember what
you learned and experienced during the day.
Sleep
disorders and chronic sleep loss can put you at risk for:
According
to some estimates, 90% of people with insomnia
-- a sleep disorder characterized by trouble falling and staying asleep -- also
have another health condition.
Sleep
specialists say that sleep-deprived men and women report lower libidos and less
interest in sex.
Depleted energy, sleepiness, and increased tension may be largely to blame.
For men
with sleep
apnea, a respiratory problem that interrupts sleep, there may be another
factor in the sexual slump. A study published in the Journal of Clinical
Endocrinology & Metabolism
in 2002 suggests that many men with sleep
apnea also have low
testosterone levels. In the study, nearly half of the men who suffered from
severe sleep
apnea also secreted abnormally low levels of testosterone during the
night.
Over
time, lack of sleep and sleep disorders can contribute to the symptoms of
depression. In a 2005 Sleep in America poll, people who were diagnosed with
depression or anxiety were more
likely to sleep less than six hours at night.
The most
common sleep disorder, insomnia,
has the strongest link to depression.
In a 2007 study of 10,000 people, those with insomnia were
five times as likely to develop depression
as those without. In fact, insomnia
is often one of the first symptoms
of depression.
Insomnia
and depression
feed on each other. Sleep loss often aggravates the symptoms of
depression, and depression can make it more difficult to fall asleep. On
the positive side, treating sleep problems can help depression and its symptoms,
and vice versa.
Most
people have experienced sallow skin
and puffy eyes
after a few nights of missed sleep. But it turns out that chronic sleep loss
can lead to lackluster skin, fine lines, and dark circles under the eyes.
When you
don’t get enough sleep, your body releases more of the stress hormone cortisol.
In excess amounts, cortisol can break down skin collagen,
the protein that keeps skin smooth and elastic.
Sleep
loss also causes the body to release too little human growth hormone.
When we’re young, human growth hormone promotes growth. As we age, it helps
increase muscle mass, thicken skin, and strengthen bones.
“It’s
during deep sleep -- what we call slow-wave sleep -- that growth hormone is
released,” says sleep expert Phil Gehrman, PhD. “It seems to be part of normal
tissue repair -- patching the wear and tear of the day.”
Trying to
keep your memory sharp? Try getting plenty of sleep.
In 2009,
American and French researchers determined that brain events called
“sharp wave ripples” are responsible for consolidating memory. The ripples also
transfer learned information from the hippocampus to the neocortex of the brain,
where long-term memories are stored. Sharp wave ripples occur mostly during the
deepest levels of sleep.
When it
comes to body weight, it may be that if you snooze, you lose. Lack of sleep
seems to be related to an increase in hunger and
appetite, and possibly to obesity.
According to a 2004 study, people who sleep less than six hours a day were
almost 30 percent more likely to become obese than those who
slept seven to nine hours.
Recent
research has focused on the link between sleep and the peptides that regulate
appetite. “Ghrelin stimulates hunger
and leptin
signals satiety to the brain and
suppresses appetite,” says Siebern. “Shortened sleep time is associated with
decreases in leptin and elevations in ghrelin.”
Not only
does sleep loss appear to stimulate appetite. It also stimulates cravings for
high-fat, high-carbohydrate foods. Ongoing studies are considering whether
adequate sleep should be a standard part of weight loss programs.
In the
“Whitehall II Study,” British researchers looked at how sleep patterns affected
the mortality of more than 10,000 British civil servants over two decades. The
results, published in 2007, showed that those who had cut their sleep from
seven to five hours or fewer a night nearly doubled their risk of death from
all causes. In particular, lack of sleep doubled the risk of death from cardiovascular
disease.
Lack of
sleep can affect our interpretation of events. This hurts our ability to make
sound judgments because we may not assess situations accurately and act on them
wisely.
Sleep-deprived
people seem to be especially prone to poor judgment when it comes to assessing
what lack of sleep is doing to them. In our increasingly fast-paced world,
functioning on less sleep has become a kind of badge of honor. But sleep
specialists say if you think you’re doing fine on less sleep, you’re probably
wrong. And if you work in a profession where it’s important to be able to judge
your level of functioning, this can be a big problem.
“Studies
show that over time, people who are getting six hours of sleep, instead of
seven or eight, begin to feel that they’ve adapted to that sleep deprivation --
they’ve gotten used to it,” Gehrman says. “But if you look at how they actually
do on tests of mental alertness and performance, they continue to go downhill.
So there’s a point in sleep deprivation when we lose touch with how impaired we
are.”
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