Sleep at 3 a.m. and then get through the day with the help of short naps? Unfortunately, napping during the day won’t restore a sleepless night, says the latest study from Michigan State University’s Sleep and Learning Lab.
“We are interested in understanding cognitive deficits related to sleep deprivation. In this study, we wanted to know if taking a short nap during the withdrawal period would alleviate these deficits, ”said Kimberly Fenn, MSU Associate Professor, Study Author and Director of MSU’s Sleep and Learning Laboratory. “We found that short naps of 30 or 60 minutes had no measurable effects.”
The study, published in Sleep magazine, is one of the first to measure the effectiveness of shorter naps – often all people have time to fit into their busy schedules.
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“While short naps had no measurable impact on alleviating the effects of sleep deprivation, we found that the amount of slow sleep participants received while napping was related to reduced sleep deprivation-related impairments,” said Fenn.
Slow-wave sleep, or SWS for short, is the deepest and most restful sleep phase. It is characterized by high amplitude, low frequency brain waves and is the phase of sleep when your body is most relaxed; Your muscles are relaxed and your heart rate and breathing are the slowest.
“SWS is the most important phase of sleep,” said Fenn. “If someone does not sleep for a while, even during the day, he builds up a need for sleep; in particular, he builds a need for SWS on SWS and spend a lot of time in this phase. “
Fenn’s research team – including MSU colleague Erik Altmann, professor of psychology, and Michelle Stepan, a new MSU alumna currently at the University of Pittsburgh – recruited 275 college-age participants for the study.
Participants did cognitive tasks in the evening on arrival at MSU’s sleep and learning laboratory and were then randomly divided into three groups: the first was sent home to sleep; the second stayed in the lab overnight and had the option of either a 30- or 60-minute nap; and the third did not nap at all in deprivation.
The next morning, participants gathered back in the lab to review the cognitive tasks that measured attention and space compliance, or the ability to complete a series of steps in a specific order without skipping or repeating them – even if they were interrupted.
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“The group that stayed overnight and took short naps were still suffering from the effects of sleep deprivation and making significantly more mistakes on tasks than their colleagues who went home and slept through the night,” said Fenn. “Every 10-minute increase in SWS reduced post-interrupt errors by about 4%.”
These numbers may seem small, but when you look at the types of errors that sleepless operators are likely to experience – like surgeons, police officers, or truck drivers – a 4% decrease in errors could potentially save lives, Fenn said.
“People who did more SWW tended to have fewer mistakes on both tasks. However, they still performed worse than those who slept,” she said.
Fenn hopes the results underscore the importance of prioritizing sleep and that naps, even if they involve SWS, cannot replace a full night’s sleep.