One sleepless night can blur the brain, but just 20 minutes of exercise or a well-timed nap may help new memories survive for days.

In a McGill University-led study, participants who exercised for 20 minutes or slept for 90 minutes after prolonged wakefulness performed about 22 percent better on a delayed memory test than those who did neither. The findings, published in Proceedings of the National Academy of Sciences (PNAS), suggest that two very different interventions can partially protect memory when adequate sleep is temporarily out of reach.

“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,” said senior author Marc Roig, a professor in 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.”