Research is showing that the daytime snooze may have benefits
and not interfere with nighttime sleep.
The nap has long been the troubled stepchild of the unassailably
hygienic and universally admired good night's sleep. At work, if
you get caught napping, it could get you into trouble or, more
mildly, sully your reputation for diligence. In studies, naps
have been linked to ill health, although usually as a
consequence, not a cause. And in sleep recommendations, naps have
taken a back seat — or been cast as a threat to nighttime sleep.
On its Web site, the American Academy of Sleep Medicine tells
people to "avoid taking naps if you can."
But lately, naps have been shedding some of their bad-for-you
image. Researchers are finding benefits. A few employers have
become accommodating of the quick snooze. And some research
suggests that instead of fretting about napping more as we get
older, we should plan on adding daytime sleep to our schedule as
a way to make up for the normal, age-related decay in the quality
of our nighttime sleep.
Getting over the hump
Naps, of course, can be an antidote to daytime sleepiness, and we
get sleepy during the day for a wide variety of reasons. There
is, in fact, a biological clock located in a cluster of cells in
the hypothalamus of the brain. Those cells orchestrate the
circadian (that is, daily) ups and downs of many physiological
processes (body temperature, blood pressure, secretion of
digestive juices), including sleep and wakefulness. As you might
expect, the usual circadian pattern is wakefulness during the day
followed by gradually increasing sleepiness in the evening, but
it's also common to have a little "hump" of midafternoon
sleepiness programmed into the circadian schedule. An afternoon
nap is one way to accommodate that hump.
In 2008, British researchers reported results of a study that
compared getting more nighttime sleep, taking a nap, and using
caffeine as ways to cope with the afternoon hump. The nap was the
Another factor in daytime sleepiness is the number of hours
you've been awake. After about 16 consecutive hours without
sleep, most of us will start to feel tired. Ideally, this
homeostatic sleep drive, as it is called, is in sync with the one
set by our circadian rhythm, so they're mutually reinforcing. But
if you work a night shift, or have problems sleeping at night,
your 16-hour allotment of wakefulness may begin — and end —
earlier, which can set you up for grogginess in the late
afternoon or early evening. A short nap won't completely reset
the timer, but it can buy you some time before the grogginess
sets in again.
How to take a good nap
Keep it short. The 20- to 30-minute nap
may be the ideal pick-me-up. Even just napping for a few
minutes has benefits. Longer naps can lead to sleep
inertia — the post-sleep grogginess that can be difficult
to shake off.
Find a dark, quiet, cool place. You
don't want to waste a lot of time getting to sleep.
Reducing light and noise helps most people nod off
faster. Cool temperatures are helpful, too.
Plan on it. Waiting till daytime
sleepiness gets so bad that you have to take a nap can be
uncomfortable and dangerous if, say, you're driving. A
regular nap time may also help you get to sleep faster
and wake up quicker.
Time your caffeine. Caffeine takes some
time to kick in. A small Japanese study published several
years ago found that drinking a caffeinated beverage and
then taking a short nap immediately afterward was the
most restful combination because the sleep occurred just
before the caffeine took effect. We're not so sure about
that approach — the mere suggestion of caffeine, in the
form of coffee taste or smell, wakes us up. Regardless of
the exact timing, you need to coordinate caffeine intake
with your nap.
Don't feel guilty! The well-timed nap
can make you more productive at work and at home.
On the job
Since 2000 or so, researchers at Harvard and elsewhere have
conducted dozens of experiments that have shown that sleep
improves learning, memory, and creative thinking. In many cases,
the edifying sleep has come in the form of a nap. For example,
several studies have shown that if people are asked to memorize
something — say, a list of words — and then take a nap, they'll
remember more of it than they would have if they hadn't taken the
nap. Even catnaps of six minutes (not counting the five minutes
it takes to fall asleep on average) have been shown to make a
difference in how well people retain information.
Robert Stickgold, a Harvard sleep researcher, says napping makes
people more effective problem solvers. His research group has
shown that taking a nap seems to help people separate important
information from extraneous details. If the nap includes REM
sleep — the phase during which dreaming occurs — people become
better at making connections between seemingly unrelated words.
Stickgold says his and others' findings argue for employer
policies that actively encourage napping, especially in today's
knowledge-based economy. Some companies have set up nap rooms,
and Google has "nap pods" that block out light and sound.
Understandably, employers are concerned about abuse: employees
catching up on sleep they should be getting on their own time.
But there may be a place for "strategic napping," especially
among people who work a night shift. Results from a New Zealand
study published in 2009 showed that air traffic controllers
working the night shift scored better on tests of alertness and
performance if they took advantage of a planned nap period of 40
minutes. Researchers in the Harvard Division of Sleep Medicine
are working with fire departments to improve sleep policies. One
of their recommendations is that firefighters on the night shift
take a nap in the late afternoon before their shift starts.
Can be a sign of trouble
Daytime sleepiness, and napping to relieve it, can also be a sign
of a health problem. Daytime sleepiness is one symptom of
Parkinson's disease, for example. In studies of older people,
regular napping has been associated with diabetes, depression,
and chronic pain, presumably because those conditions adversely
affect nighttime sleep. Indeed, it only stands to reason that
napping might be a coping mechanism for those who can't sleep
well at night, no matter the age or the reason. Sleep problems,
daytime grogginess, fatigue, a desperate need to nap — all are
noteworthy, and suitable topics of conversation with your doctor.
Bad nighttime sleep may be a cause of napping, but what's less
clear is whether the reverse is true: does napping cause bad
nighttime sleep? That's been the belief, but a couple of studies
haven't found an association between napping and complaints about
nocturnal sleep. In fact, a few studies have shown that napping,
and the ability to nap, are more common in older adults who sleep
well at night than in those who don't. And it's been suggested
that a nap might be an appropriate adaptation for older people
who, as a rule, sleep an hour less per night than younger people
and wake up earlier.
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