Scrap the nap: Study shows short naps don't relieve sleep deprivation


Date:
August 12, 2021
Source:
Michigan State University
Summary:
The latest study shows that short naps are ineffective in mitigating
the potentially dangerous cognitive effects of sleep deprivation.



FULL STORY ==========================================================================
A nap during the day won't restore a sleepless night, says the latest
study from Michigan State University's Sleep and Learning Lab.


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"We are interested in understanding cognitive deficits associated with
sleep deprivation. In this study, we wanted to know if a short nap during
the deprivation period would mitigate these deficits," said Kimberly Fenn, associate professor of MSU, study author and director of MSU's Sleep and Learning Lab. "We found that short naps of 30 or 60 minutes did not show
any measurable effects." The study was published in the journal Sleep
and is among the first to measure the effectiveness of shorter naps --
which are often all people have time to fit into their busy schedules.

"While short naps didn't show measurable effects on relieving the effects
of sleep deprivation, we found that the amount of slow-wave sleep that participants obtained during the nap was related to reduced impairments associated with sleep deprivation," Fenn said.

Slow-wave sleep, or SWS, 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 your body is most relaxed; your muscles are at ease,
and your heart rate and respiration are at their slowest.

"SWS is the most important stage of sleep," Fenn said. "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 SWS. When individuals go to sleep each night, they will soon enter into SWS and
spend a substantial amount of time in this stage." Fenn's research team
-- including MSU colleague Erik Altmann, professor of psychology, and
Michelle Stepan, a recent MSU alumna currently working at the University
of Pittsburgh -- recruited 275 college-aged participants for the study.



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The participants completed cognitive tasks when arriving at MSU's Sleep
and Learning 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, 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," Fenn said. "However, every 10-minute increase in SWS 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,
Fenn said.

"Individuals who obtained more SWS tended to show reduced errors on
both tasks.

However, they still showed worse performance than the participants who
slept," she said.

Fenn hopes that the findings underscore the importance of prioritizing
sleep and that naps -- even if they include SWS -- cannot replace a full
night of sleep.

========================================================================== Story Source: Materials provided by Michigan_State_University. Original
written by Caroline Brooks. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Michelle E Stepan, Erik M Altmann, Kimberly M Fenn. Slow-wave sleep
during a brief nap is related to reduced cognitive deficits during
sleep deprivation. Sleep, 2021; DOI: 10.1093/sleep/zsab152 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210812123122.htm

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