If you’ve been struggling to catch some Z’s, you know all too well that a poor night’s sleep can affect more than just your energy levels. Sleep deficiency has been linked to several chronic health issues, according to the National Institutes of Health (NIH), and is known to interfere with cognitive function and the ability to form memories.
The good news? New research suggests that at least one of those problems—trouble with memory—can be ameliorated by either taking a nap or exercising.
A study published in PNAS found that both a 90-minute nap and a 20-minute exercise session “substantially protected memory after sleep loss,” says Marc Roig, Ph.D., study co-author and professor in the school of physical and occupational therapy at McGill University. “Participants who exercised or napped remembered about 22% more information than those in the control group, and the benefits of the two interventions were remarkably similar.”
So, should you carve out time for a quick nap or a gym session after a poor night’s sleep? Ahead, experts break down the study’s results and what they mean for you.
Meet the experts: Marc Roig, Ph.D., study co-author and professor in the school of physical and occupational therapy at McGill University; Brendan P. Lucey, M.D., M.S.C.I., F.A.N.A., F.A.A.S.M., professor in the department of neurology at the University of Minnesota Medical School.
What did the study find?
The study enrolled 54 healthy adults, aged 18 to 35, and kept them awake for 30 hours. Participants were then divided into three groups—those who took a 90-minute nap, those who rode an indoor bike moderately to intensely for 20 minutes, and a control group who did neither—and given a memory encoding task. Three days later, the participants returned and were given a surprise memory test.
Electroencephalography (EEG) was used to monitor brain activity during both the memory encoding task and the memory test, allowing the researchers “to examine both memory performance and the brain processes underlying that performance,” Roig says.
Ultimately, the researchers found that the participants assigned to nap or exercise performed about 22% better on the memory test.
“What excites us scientifically is that the study highlights the brain’s extraordinary flexibility. Even under severe sleep deprivation, the brain was able to preserve memory by recruiting different neural pathways. Understanding this adaptability may help us develop better strategies to protect cognitive function in the future,” Roig says. “We are now investigating whether training people for several weeks can make their brains more resilient against the effects of sleep loss on memory.”
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Why might exercise and naps help with memory?
“Sleep does two main things to support memory,” explains Brendan P. Lucey, M.D., M.S.C.I., F.A.N.A., F.A.A.S.M., professor in the department of neurology at the University of Minnesota Medical School. “During sleep, the brain replays and stabilizes what was learned during the day. Sleep also down-scales synaptic strength that builds up during the day so there is capacity to encode more learning the next day.” When sleep is impaired, these processes can be as well.
So, how do exercise and naps mitigate this harm? The researchers analyzed the EEG data to find out. “What surprised us most was that they achieved these benefits through different neural pathways,” Roig says. “Napping seemed to help by reducing sleep pressure and restoring a brain state that was more receptive to learning. Exercise appeared to help the brain use its available memory-related resources more efficiently during learning.”
What are the study’s limitations?
Roig notes that the participants were uniformly young and healthy, and the study’s findings may not apply to all people. Additionally, the study only looked at memory, which is just one aspect of cognitive performance; it’s not clear if exercise or naps can help with the other ways sleep deprivation affects cognition.
What’s the takeaway?
Overall, Dr. Lucey says that after a poor night’s sleep, it’s worth trying exercise or a nap before attempting to learn new material. However, he cautions, “it is key that the interventions need to be done before the learning, as there is no evidence they will rescue memory performance of information you’ve already learned.”
It is exciting to learn that two highly accessible, low-cost interventions—napping and exercising—can have a protective effect on memory. However, Roig stresses that napping and exercising aren’t proper substitutes for a good night’s sleep.
“We see these interventions as tools that may help mitigate some of the consequences of unavoidable sleep loss, not as a cure for insufficient sleep,” he says. “The most important advice remains simple: prioritize sufficient sleep whenever possible. No intervention can replace all of the biological functions of sleep.”
Dr. Lucey agrees. “Napping and exercise are not alternatives to good quality sleep,” he says. “Sleep has positive effects on human health other than memory, including metabolic, cardiovascular, and immune function.”
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