Sleep and learning
Even in well-rested people, naps can improve performance
in areas such as reaction time, logical reasoning and symbol
recognition, as Cote described in a 2009 review (Journal of Sleep
Research, 2009). They can also be good for one’s mood.
A study by University of Michigan doctoral student Jennifer
Goldschmied and colleagues found that after waking from a
60-minute midday nap, people were less impulsive and had
greater tolerance for frustration than people who watched an
hourlong nature documentary instead of sleeping (Personality
and Individual Differences, 2015). “Frustration tolerance is
one facet of emotion regulation,” says Goldschmied. “I suspect
sleeping gives us more distance [from an emotional event] —
it’s not just about the passing of time.”
Researchers are only just starting to understand how naps
might affect emotion regulation, Goldschmied adds. But
the benefits of napping for memory and learning are well
described. “Even a brief bit of sleep helps reinforce learned
material,” she says.
For many types of memory, the benefits of a nap are
substantial, says Sara Mednick, PhD, a psychologist at the
University of California, Riverside. Take perceptual learning.
Previous research demonstrated that people perform better on
a visual texture-distinguishing task after a night of sleep than
they do immediately after learning it. Further, Mednick and
colleagues found people performed just as well on the test after
a 60- to 90-minute nap as they did after a full night of slumber
(Nature Neuroscience, 2003).
“What’s amazing is that in a 90-minute nap, you can get
the same [learning] benefits as an eight-hour sleep period,”
Mednick says. “And actually, the nap is having an additive
benefit on top of a good night of sleep.”
In another experiment, Mednick found that an afternoon
nap was about equal to a dose of caffeine for improving
perceptual learning. But in other ways, a midday doze might
trump your afternoon latte. She found people who napped
performed better on a verbal word-recall task an hour after
waking compared with people who took caffeine or a placebo
(Behavioural Brain Research, 2008). While caffeine enhances
alertness and attention, naps boost those abilities in addition
to enhancing some forms of memory consolidation, Mednick
A catnap can benefit performance in a variety of other
memory domains as well. In one recent example, Axel
Mecklinger, PhD, at Saarland University in Germany, and
colleagues studied memory
recall in volunteers who
learned single words as
well as meaningless word
pairs (such as “milk-taxi”).
Half of the participants
then took a 90-minute nap,
while the others watched a
DVD. Then the researchers
retested participants’ recall.
remembered about the
same number of single
words. This was a test
of so-called item memory — the type of memory you use
when you recall a grocery list. But the nappers remembered
significantly more of the word pairs. This type of “associative
memory” is involved in remembering things that are linked,
such as putting a name with a face. And unlike item memory,
the hippocampus plays a strong role in associative memory,
suggesting that naps benefit hippocampus-dependent
learning (Neurobiology of Learning and Memory, 2015).
Other research builds the case that the hippocampus benefits
from a nap. Matthew Walker, PhD, a professor of psychology at
the University of California, Berkeley, and colleagues recruited
volunteers to tax their associative memories by learning a long
list of name-face pairings.
Half the participants then took 90-minute midday naps.
That evening, the participants were given a new round of
learning exercises with novel pairings. Those who hadn’t
napped didn’t perform as well on the evening test as they had
in the morning. But the nappers did better on the later test,
suggesting the sleep had boosted their capacity for learning
(Current Biology, 2011).
Not all the nap research is so glowing, however. Some
studies have suggested that excessive sleep and daytime naps
are associated with higher levels of C-reactive protein, a
marker for systemic inflammation (which has been linked
to a host of ills, including cancer, diabetes, depression and
heart disease). Yet other research suggests naps can improve
immune function. Indeed, a review by Rebecca Spencer,
Researchers are only just starting to
understand how naps might affect emotion
regulation. But the benefits of napping for
memory and learning are well described.