Naps aren't enough
By Science News Staff / Source
In a new study, researchers from the University of Pittsburgh and Michigan State University tested the effect of brief naps (30- or 60-min) during a period of sleep deprivation.
Slow-wave sleep is the deepest and most restorative stage of sleep.
It is marked by high
amplitude, low frequency brain waves and is the sleep stage when our body is
most relaxed; muscles are at ease, and heart rate and respiration are at their
slowest.
“Slow-wave sleep is the most important stage of sleep,” said Dr. Kimberly Fenn, director of the Sleep and Learning Lab at Michigan State University.
“When someone goes
without sleep for a period of time, even just during the day, they build up a
need for sleep.”
“In particular, they
build up a need for slow-wave sleep. When individuals go to sleep each night,
they will soon enter into slow-wave sleep and spend a substantial amount of
time in this stage.”
For the study, Dr. Fenn
and colleagues recruited 275 college-aged participants.
The volunteers completed
cognitive tasks when arriving at the lab in the evening and were then randomly
assigned to three groups.
The first was sent home
to sleep; the second stayed at the lab overnight and had the opportunity to
take either a 30 or a 60 minute nap; and the third did not nap at all in the
deprivation condition.
The next morning, the
participants reconvened in the lab to repeat the cognitive tasks, which
measured attention and placekeeping, or the ability to complete a series of
steps in a specific order without skipping or repeating them — even after being
interrupted.
“The group that stayed
overnight and took short naps still suffered from the effects of sleep
deprivation and made significantly more errors on the tasks than their
counterparts who went home and obtained a full night of sleep,” Dr. Fenn said.
“However, every 10-min
increase in slow-wave sleep reduced errors after interruptions by about 4%.”
“These numbers may seem
small but when considering the types of errors that are likely to occur in
sleep-deprived operators — like those of surgeons, police officers or truck
drivers — a 4% decrease in errors could potentially save lives.”
“Individuals who
obtained more slow-wave sleep tended to show reduced errors on both tasks.
However, they still showed worse performance than the participants who slept.”
“We hope that the
findings underscore the importance of prioritizing sleep and that naps — even
if they include slow-wave sleep — cannot replace a full night of sleep.”
The findings were
published in June 2021 in the journal Sleep.
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Michelle E. Stepan et
al. Slow-wave sleep during a brief nap is related to reduced cognitive
deficits during sleep deprivation. Sleep, published online June 22,
2021; doi: 10.1093/sleep/zsab152
