A 20-minute workout or a 90-minute nap may help the brain hold onto new memories after a full night without sleep, according to new research from McGill University. The study found that healthy young adults who exercised or napped after 30 hours without sleep performed significantly better on memory tests than those who did neither.
The findings were published in Proceedings of the National Academy of Sciences. Researchers enrolled 54 healthy adults between the ages of 18 and 35. None of them had a history of sleep disorders, worked night shifts, or used sleep medications. Participants were divided into three groups: one exercised, one napped, and one received no intervention.
After the 30-hour period of wakefulness, participants attempted to memorize 150 color images. Three days later, after a recovery period, they returned for a surprise memory test using those same images.
Both the exercise and nap groups outperformed the control group by a measurable margin. According to Healthline, study co-author Marc Roig, a professor of physical and occupational therapy at McGill University and director of the Memory and Motor Rehabilitation Laboratory, described the results directly.
"We found that both a 20-minute bout of moderate-to-vigorous exercise and a 90-minute nap protected the brain's ability to form new memories after 30 hours without sleep," Roig said. "Participants in both intervention groups remembered about 22% more information than those who received no intervention."
The study focused specifically on episodic memory, which is the type of memory that allows people to recall events and experiences. Researchers noted that this form of memory is particularly sensitive to sleep loss. Sleep deprivation can interfere with the encoding stage of memory, which is the process by which the brain takes in and stores new information.
Vernon Williams, a sports neurologist and founding director of the Center for Sports Neurology and Pain Medicine at Cedars-Sinai Orthopaedics and Sports Medicine in Los Angeles, was not involved in the research but commented on the findings. The important message, he said, is that "more than one strategy is effective in protecting cognitive function when short-term sleep loss is unavoidable."
Researchers were careful to note that neither a workout nor a nap should be considered a substitute for regular, healthy sleep. The participants in the study were a narrow group, all young and healthy adults with no sleep-related conditions, which means the results may not apply to older adults, people with sleep disorders, or those who experience chronic sleep deprivation rather than a single sleepless night.
The study participants had no significant differences among them in age, sex, chronotype, physical activity level, cardiorespiratory fitness, or sleep patterns before the study began, which the researchers said helped isolate the effects of the interventions.
The practical implications of the research could be meaningful for shift workers, medical professionals, new parents, and others who regularly face nights with little or no sleep. Having two accessible options, one requiring only a pair of sneakers and 20 minutes, the other requiring only a place to lie down for an hour and a half, gives people flexibility depending on their circumstances.
The research adds to a growing body of work examining how the brain compensates for sleep loss and what behavioral strategies may reduce the cognitive cost of going without sleep.
