PhD, found the picture is almost comically muddy:
Various studies in various populations have found
that too much sleep, too little sleep, frequent naps
and infrequent naps can all be linked to elevated
C-reactive protein. Ultimately, more work needs to
be done to understand what patterns of nighttime
and daytime sleep are healthy, and for whom (Sleep
Other concerns about the downside of naps are better
established. The biggest concern is that daytime sleep can
disrupt nighttime sleep. Sleeping too much during the day can
interfere with the ability to fall asleep and stay asleep at night.
That’s why, says Siegel, “one of the standard instructions at sleep
disorder centers is to tell people not to nap.”
Siegel admits he’s never been a napper himself. His research
suggests he’s hardly alone in that respect. In a recent study, he
and his colleagues tracked the sleep patterns of hunter-gatherer
groups in Tanzania, Namibia and Bolivia. These people are
thought to live much like our ancestors did some 10,000 years
ago. And while nearly all of them took a break from the sun
during the heat of midday, none of the 94 individuals they
followed took regular naps.
“I’m not saying we should do everything our ancestors did,
but it suggests that napping is not a part of the ancient human
physiology,” Siegel says.
Still, just because Siegel’s subjects didn’t nap doesn’t mean
naps have no benefit, says Cote. “Sleep is a behavior, and human
behavior is highly adaptable,” she says. “We get sleep in many
ways. After a certain age, naps are not biologically necessary, but
napping does have benefits.”
It’s likely that some people benefit more than others,
though. “A certain percentage of people are regular nappers. If
you ask these people, they’ll be aware they’re getting benefit:
They’re more alert, have better moods and they’re feeling
sharper,” Cote says.
But others — including Cote — wake up groggy after naps
and drag the rest of the day. She believes people who choose to
nap regularly are predisposed to get more out of it. Some of her
own laboratory research suggests that frequent nappers show
greater improvements in performance following a midday nap
than people who don’t often nap (Biological Psychology, 2006).
“I think we self-select this behavior,” she says.
Other research is starting to piece together clues about who
benefits from naps, and why. In not-yet-published research,
Goldschmied and colleagues found evidence that people who
self-identify as night owls tend to show bigger improvements in
performance following a nap, compared with their early-bird
The way you move through the stages of the sleep cycle may
also play an important part in whether you’re a born napper
or not. Mednick (who loves a nap when she can get it) says
people who nap regularly appear to stay in lighter stages of sleep
that they can wake from easily, while infrequent nappers often
sink into deeper sleep and wake up woozy. “It appears there’s a
qualitative difference to naps,” she says. n
• Mednick, S., with Ehrman, E. (2006). Take a nap!
Change your life. New York, NY: Workman Publishing.
• Milner, C. E., & Cote, K. A. (2009). Benefits of napping
So you want to take a nap?
in healthy adults: Impact of nap length, time of day, age,
and experience with napping. Journal of Sleep Research, 18,
272–281. doi: 10.1111/j.1365-2869.2008.00718.x
• Studte, S., Bridger, E., & Mecklinger, A. (2015).
Nap sleep preserves associative but not item memory
performance. Neurobiology of Learning and Memory, 120,
84–93. doi: 10.1016/ j.nlm.2015.02.012
If you’re inclined toward a siesta, science offers some
pointers for timing it right.
Go short. Naps of about 20 minutes are great for
getting a boost. “If you’re seeking alertness, clarity
of the mind, pushing the reset button, that can all
happen with a 20-minute nap,” Mednick says.
Go big. During sleep, adults cycle through a series
of sleep stages, with a single cycle lasting about 90
minutes. If you can spare an hour and a half, that’s a
great length for a nap that confers all the benefits of
each sleep stage, Mednick says.
Don’t split the difference. In the middle of a sleep
cycle, we sink into a deep, heavy stage of sleep that’s
hard to wake from. If you try to rise from a nap after
40 to 60 minutes, you’re more likely to be stuck with a
groggy feeling that lingers all afternoon.