I have always felt that a little snooze in the middle of the afternoon works better for me than a jolt of caffeine. However, the guilt induced by the very thought of sleeping during the day (especially at work) has kept me drinking coffee or tea instead of crashing on my desk and drooling on my keyboard.
But now, I feel a little better about my afternoon break, because according to preliminary investigations at UC Berkeley, it turns out that a siesta can actually reboot the brain and allow for improved afternoon learning.
In the sleep study, 39 college students were divided into two groups – nap and no-nap. The participants were subjected to a rigorous learning task at noon. The task was intended to activate the hippocampus, a part of the brain that helps process fact-based memories. Both groups performed at comparable levels.
At 2 p.m., the nap group took a 90-minute snooze while the no-nap group stayed awake. Later that day, at 6 p.m., participants performed a new round of learning exercises. Those who remained awake throughout the day became worse at learning. In contrast, those who napped did markedly better and actually improved in their capacity to learn.
Those who remained awake performed about 10 percent worse on the tests than those who napped. Normal folk’s ability to learn typically declines about 10 percent between noon and 6 p.m., but those succumbing to a siesta were able to negate that decline.
“Sleep not only rights the wrong of prolonged wakefulness but, at a neurocognitive level, it moves you beyond where you were before you took a nap,” said Matthew Walker, in a news release from UC Berkeley. Dr. Walker is an assistant professor of psychology at UC Berkeley and the lead investigator of these studies.
These findings reinforce the hypothesis that sleep is needed to clear the brain’s short-term memory storage and make room for new information. Sleep researchers have established that fact-based memories are temporarily stored in the hippocampus before being sent to the brain’s prefrontal cortex, which may have more storage space.
“It’s as though the e-mail inbox in your hippocampus is full and, until you sleep and clear out those fact e-mails, you’re not going to receive any more mail. It’s just going to bounce until you sleep and move it into another folder,” Walker said.
Walker presented his preliminary findings on Sunday, Feb. 21, at the annual meeting of the American Association of the Advancement of Science (AAAS) in San Diego, CA. In addition to Walker, co-investigators of these new findings are UC Berkeley post-doctoral fellow Bryce A. Mander and psychology undergraduate Sangeetha Santhanam.
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UC Berkeley news release