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 While previous research has linked frequent naps to better memory in
babies as young as 6 months, the current study examined the impact
of a single 1.5- to 2-hour nap for infants half that age.
The experiment tested memory by counting on babies to quickly tire
of looking at faces they remember. Researchers showed infants one of
two cartoon characters with distinctive facial features, let some of
the babies nap, then showed all of the babies both characters to see
which one captured their attention longer.
More than half of the babies who napped turned their gaze to the
unfamiliar cartoon face, indicating they remembered what they saw
before they slept, the study found. But without a nap, babies
appeared to randomly choose which face they looked at, suggesting
they forgot what they had seen before and found both cartoons new
and interesting.
“Three month-old babies could only remember the newly shown face if
they had a nap right after seeing the new cartoon face,” said lead
study author Dr. Klara Horvath, who conducted the study at the
University of Oxford in the UK.
“It seems for them having a short period of sleep is necessary to be
able to consolidate memories, otherwise they just forget the newly
learned information,” Horvath, now a pediatrics researcher at
Semmelweis University in Budapest, said by email.
For the study, researchers also looked at something known as sleep
spindles, or spikes of brain activity thought to be involved in
consolidation of memories. Sleep spindles show up on
electroencephalogram (EEG) tests that examine brain wave patterns.
Among babies who napped, infants who also had more sleep spindles
appeared to become familiar with the faces more quickly, suggesting
that the brief periods of rest might influence how fast the brain
processes information, researchers report in Developmental Science.
One limitation of the study is its small size - only 45 infants
altogether. There were just 28 babies in the nap group, and only 15
had EEG data.
Another drawback is that all the babies in the nap group saw the
cartoon faces right before they went to sleep, making it impossible
to rule out the potential for that learning experience to influence
the number of sleep spindles, the researchers note.
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The study also didn’t find a difference in memory based on the
duration of babies’ naps, which suggests that more sleep may not
always be best when it comes to learning, said Sabine Seehagen, a
psychology researcher at the University of Waikato in New Zealand
who wasn’t involved in the study.
“It is possible that some undetermined minimum duration of sleep was
all that was needed for infants to ‘succeed’ in the task,” Seehagen
said by email. “We also don’t know how effective the nap was
compared to, say, a full night’s sleep and we don’t know if several
naps might have added benefits.”
Still, the findings offer fresh evidence that sleep is critical to
normal development even at a very young age, said Gina Poe, a
researcher in physiology and psychiatry at the University of
California, Los Angeles, who wasn’t involved in the study.
“We neuroscientists and biopsychologists have a long way to go
before we understand how long different types of memory
consolidation tasks take and why,” Poe said. “But once the job is
done, more sleep may be akin to the builders hammering more nails
into a structure that is already securely connected.”
That doesn’t mean that parents should cut short naps to help babies’
development, however.
“Even if the job that you are tracking is done with a short nap,
there may be other brain tasks that the brain is attending to during
a longer nap that we don’t know about,” Poe added. “So never wake a
sleeping baby.”
SOURCE: http://bit.ly/2eRfhnV Developmental Science, online July 18,
2017.
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