Naps Help Babies Learn
and Retain New Information
Anyone who grew up in a large family likely remembers hearing
"Don't wake the baby." While it reinforces the message
to older kids to keep it down, research shows that sleep also
is an important part of how infants learn more about their new
Rebecca Gomez, Richard Bootzin and Lynn Nadel in the psychology
department at the University of Arizona in Tucson found that babies
who are able to get in a little daytime nap are more likely to
exhibit an advanced level of learning known as abstraction.
Nadel, a Regents' Professor at the UA, has described the group's
work (Early Learning in Infants May Depend on Sleep) in a session
at the American Association for the Advancement of Science annual
meeting in San Diego on , Feb. 21.
In their research, Nadel and his colleagues played recordings
of "phrases" created from an artificial language to
four dozen 15-month-old infants during a learning session. Their
methodology included repeatedly playing phrases like "pel-wadim-jic"
until the babies became familiar with them.
These phrases contained three units, with the first and last
unit forming a relationship. In this example, the first word,
"pel," predicts the last, "jic." Even though
these are nonsensical sounds, the language created for the test
shares some similarity with structure commonly found in subject-verb
agreement in English sentences.
Prior to being tested, some infants learning this faux language
took their normally scheduled naps. Others were scheduled at a
time when they would not nap following the session. When the infants
returned to the lab, they again heard the recordings -- along
with a set of different phrases in which the predictive relationship
between the first and last words were new.
By carefully watching the babies' facial expressions as they
listened to both old and new phrases, the researchers were able
to rate their level of attention. They found that babies' longer
gazes at a flashing light that coincided with the phrases signaled
attention, which indicated that they had learned a particular
phrase or relationship.
Differences arose between the infants who had napped and those
who had not. The infants who did not sleep after the sessions
still recognized the phrases they had learned earlier. But those
babies who had slept in between sessions were able to generalize
their knowledge of sentence structure to draw predictive relationships
to the new phrases. This suggests that napping supports abstract
learning -- that is, the ability to detect a general pattern contained
in new information.
In follow-up work, the UA researchers have shown that infants
must have their naps within four hours of listening to the artificial
language in order for them to demonstrate this beneficial abstraction
effect. Those who failed to nap within that time, but slept normally
that evening, failed to show the abstraction effect the next day.
"It's a fairly nuanced story," Nadel said. "What
we know is that infants have mostly REM sleep, given the type
of sleep they have, given how their brains are developed at that
point. And they have to get some of that sleep within a reasonable
amount of time after inputting information in order to be able
to do abstracting work on it. If they don't sleep within four
to eight hours, they probably just lose the entire thing,"
What this should reinforce for parents, he said, is that while
it obviously is important to give infants and young children the
kind of stimulation that comes from reading, talking and exposing
them to lots of words, these stimuli need to happen within the
context of a reasonably well-regulated daily cycle that includes
February 22, 2010