An hourly afternoon nap could mean a boost for healthy mental function for older adults.
In a study published in the Journal of the American Geriatrics Society, researchers examined information given by 3,000 Chinese adults aged 65 years and older to learn whether taking an afternoon nap had any effect on mental health. The study said the naps should be brief in duration.
“Moderate-duration naps taken during the post-lunch dip would be associated with better cognitive performance in Chinese older adults and that extended nap duration would be associated with shorter nighttime sleep duration,” the study said. “Napping during the post-lunch dip period may lead to better cognitive function because it has greater recuperative value than napping at other times of the day.”
Almost 60 percent of the individuals involved in the study said they napped after lunch in the afternoon. Participants said they napped between 30 minutes to more than 90 minutes, with most taking naps lasting about an hour.
Several tests were administered to assess the participants’ mental status. They were asked simple questions about the date and season of the year, and completed basic math problems.
The participants were asked to memorize and remember words, copy drawings of simple geometric figures, and answer questions about their napping and nighttime sleeping habits. Nappers were divided into four different groups: non-nappers, short nappers who nap less than 30 minutes, moderate nappers who nap 30 to 90 minutes, and extended nappers who nap more than 90 minutes.
Similarly, groups were distinguished for nighttime sleeping habits. The four nighttime sleep groups included: very short sleepers who slept less than five hours a night, short sleepers who slept five to seven hours a night, normal sleepers who slept seven to nine hours a night, and long sleepers who slept more than nine hours a night.
The study’s results indicated that those who took an hour-long nap after lunch performed better on the mental tests compared to those who didn’t. Those who took no naps, short naps or even longer naps experienced decreases in their mental ability that were estimated to be four to six times greater than those who took hour-long naps.
“In general, [the average] nighttime sleep duration increased with amount of post-lunch napping,” the study said. “There was also evidence that non-nappers and extended nappers had lower adjusted overall cognition scores.”
Those who did not nap, along with those who took shorter or longer naps, experienced about the same decline in mental abilities that a five-year increase in age would be expected to cause. The study said other research findings were similar.
“A study found that napping for less than one hour and longer than one hour were negatively associated with incidence of cognitive impairment at two-year follow up,” the study said. “Napping for longer than one hour was also adversely associated with cognitive decline at ten-year follow-up.”
The study said it depended on patients’ self reports, so it could have introduced a bias. Funding was assisted in part by a grant from the University of Pennsylvania and is based on the baseline of the China Health and Retirement Longitudinal Study.