We’ve all been there: running on just four hours of sleep with a long day ahead, knowing that coffee will only provide limited help.
Should you fit in a nap, or opt for a workout?
A recent study published in the Proceedings of the National Academy of Sciences indicates that both a nap and a 20-minute workout can have a comparable effect on memory.
Researchers at McGill University in Canada conducted an experiment with 54 healthy young adults who stayed awake for an intense 30 hours under laboratory conditions. They were then divided into three groups.
One group engaged in 20 minutes of moderate-to-vigorous cycling, another took a 90-minute nap, and a control group sat on a stationary bike without pedaling for 20 minutes.
Afterward, participants were shown a series of images without being instructed to memorize them. Three days later, they were tested on their ability to recognize these images.
Both the nap and exercise groups performed significantly better than the control group, with 23 percent better recognition for the nappers and 21 percent for the exercisers. Statistically, there was no significant difference between the two interventions.
This finding aligns with a 2023 study from the University of Portsmouth, which demonstrated that 20 minutes of moderate cycling enhanced cognitive performance in sleep-deprived individuals, even in low-oxygen conditions.
The unique aspect of this new study is that researchers also monitored participants’ brain activity using electroencephalography (EEG). They discovered that both groups achieved similar outcomes through distinct neurological processes.
In the nap group, researchers observed signs of reduced sleep pressure and fatigue in the brain, such as a decrease in slow-wave activity. This indicated that the 90-minute nap effectively compensated for lost sleep.
The exercise group, however, did not exhibit these markers of reduced fatigue. Despite this, their memory improvement correlated with signals related to how efficiently their brains processed the images during viewing.
In essence, while the nap provided rest to the brain, the exercise enhanced its functionality without alleviating fatigue.
“Sleep loss affects nearly every aspect of how we think and function, but many people can’t simply stop what they’re doing and get more sleep,” says Marc Roig, the study’s senior author and a sports scientist at McGill’s School of Physical and Occupational Therapy.
“Our findings show that even a brief bout of exercise may help preserve one of our most important cognitive abilities.”
This is particularly relevant for individuals who cannot choose to nap, such as nurses, pilots, new parents, and night shift workers, as neuroscientist Madhura Lotlikar, the study’s first author, notes.
“Exercise is accessible, inexpensive, and easy to implement. That makes it a promising tool to help people stay cognitively sharp when sleep is limited,” explains Lotlikar.
However, neither a workout nor a nap is a substitute for a good night’s sleep. The researchers emphasize that these are temporary measures, not long-term solutions for sleep deprivation.
This is crucial, given that 20 to 40 percent of adults worldwide do not get sufficient sleep, a deficit costing countries like the US, UK, Germany, Japan, and Canada an estimated $680 billion annually in lost economic productivity.
Related: First-of-Its-Kind Study Shows Just One Extra Hour of Sleep a Night Raised College Students’ Grades
So, if you’re facing a day with only four hours of sleep, a nap could be your best option. If napping isn’t possible, a brisk 20-minute walk or cycling session may not only distract you from fatigue but also provide a genuine cognitive boost.
The research has been published in the Proceedings of the National Academy of Sciences.
This article was fact-checked by Rebecca Dyer and edited by Rebecca Dyer. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
