Napping, that sweet slide into slumber, is considered an indulgence. Now, however, researchers think it may actually be good for some of us.
A study published in the online journal General Psychiatry concludes that regular afternoon naps appear to boost older adults' cognitive functions. This could be a win-win for people over the age of 60, who are prone to both sleep-pattern disruptions and neurodegenerative decline.The research included 2,214 healthy people 60 and older, residents of several large cities in China. A total of 1,534 napped regularly; 680 did not. All the participants took a series of cognitive assessments, including the Mini-Mental State Exam (MMSE), to check for dementia. The results: nappers tested "statistically higher" on average compared to non-nappers.
This comes as no surprise to Alberto Ramos, M.D., M.S.P.H., associate professor of neurology and research director of the University of Miami Health System's Sleep Disorders Program.
"We've finally come to acknowledge how important, how integral sleep is for brain functions," Dr. Ramos says. "We know that a lot of what we learn is consolidated during sleep and that toxins that accumulate in our brains also seem to get flushed out in sleep."
Dr. Ramos' research may serve as a corollary to the General Psychiatry study.
He was the senior author of a new study published last year in Alzheimer's & Dementia: The Journal of the Alzheimer's Association. Along with other UHealth researchers and eight other institutions, Dr. Ramos and the team looked at sleep patterns and cognitive functions of 1,035 Hispanic adults between the ages of 45 to 64 years from the Hispanic Community Health Study/Study of Latinos. Their current cognitive functions were compared with measurements taken seven years earlier.
The study concluded that taking longer to fall asleep was linked to lower verbal memory, verbal learning, and other cognitive functions. And the longer it took, the higher the cognitive decline. Researchers speculate this may be because the middle-aged Hispanics in the study had shorter periods of deep sleep. (Interestingly enough, sleeping too much was also linked to a decline in cognitive function.)
This information could help predict – and reduce – the risk of cognitive decline in a particularly vulnerable population. Hispanics' risk of developing dementia is two to four times higher than their non-white counterparts, and the lag in falling asleep could serve as a potential marker.
As for naps, Ramos and his team found that they were actually associated with less decline in memory function, which dovetails with the study out of China.
Nevertheless, not all napping is created equal.
The General Psychiatry cognitive assessment study in China defined naps as periods of at least five consecutive minutes of sleep during the daytime, but no more than two hours. These naps were taken after lunch, and frequency ranged from every day to once a week. However, two-hour naps may be counterproductive to general sleep hygiene, possibly leading to more trouble falling asleep at night. Previous sleep research has also found that longer naps were associated with a 34% higher risk of cardiovascular disease, especially for nappers who slept more than six hours per night. In comparison, shorter naps (30 to 45 minutes) were not found to be risky and could possibly improve heart health.
"Short naps are better, 30 minutes or less," Dr. Ramos says.
"The purpose is to give you a jolt of energy in the middle of the day."
In addition to duration, the timing of the nap is also essential. Too much of a good thing in the late afternoon can lead to sleep inertia, a groggy and disoriented state, he adds.
Before incorporating nap time into your day, take an inventory of your nighttime sleep habits. Most adults should get 7 to 8 hours of sleep in 24 hours. Ideally, this would happen continuously and at night. But medications, health problems, and sleep disorders can disturb restful slumber. Our 24/7, always-connected lifestyle can sacrifice much-needed sleep as well, as we pack more work into our waking hours.
If you're among the lucky who achieve sleep nirvana, a daytime snooze may not be essential. However, naps appear to work best for older adults because deep sleep is harder to achieve as we grow older. If you're having frequent nighttime waking, a nap increases your total sleep time, which in turn will pump up your cognitive abilities.
"Sleep should be part of any healthy lifestyle planning," Dr. Ramos says. "We need to think of in the same as exercising and proper nutrition."
Ana Veciana-Suarez, Guest Columnist
Ana is a regular contributor to the University of Miami Health System. She is a renowned journalist and author who has worked at The Miami Herald, The Miami News, and The Palm Beach Post. Visit her website at anavecianasuarez.com or follow @AnaVeciana on Twitter.
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