One sleepless night can make you feel dazed and confused, and your memory span may be compromised, but a new study has proved there is a surprisingly simple solution. A short period of moderate exercise may be just as effective as a two-hour nap in boosting your brain’s ability to consolidate long-term memories. McGill University researchers announced this news in Proceedings of the National Academy of Sciences. Fifty-four healthy, young adults in good sleep health were kept awake in the lab continuously for 30 hours by researchers.
After this period of sleep deprivation, subjects were randomly assigned to one of three experimental conditions. Participants either did 20 minutes of moderate to vigorous intensity cycling on a stationary bike; nor did they participate in a 90-minute nap. The control subjects did neither.
As soon as the activity, or lack thereof, was completed, the subjects viewed a sequence of photographs. Two days later they returned to the lab and were given an unexpected memory recall test, testing their ability to continue to recognize those photographs. The findings were startling. The exercise and nap interventions both much improved memory by approximately twenty-two percent against the control condition.
Cyclists exhibited an approximately twenty-one percent improvement while nappers showed approximately twenty-three percent. Statistically there was no difference between the two interventions in their ability to protect episodic memorythe sort that permits remembering past events and experiences and which appears to be in particular sensitive to sleep deprivation. The surprising part about the finding is that exercise and sleep had the same effect through the different biological pathways.
Brain scans showed that the nap lowered both sleep pressure and mental fatigue. The act of napping, in effect, allowed the brain to have more room for further information. In contrast exercise did not decrease fatigue but allowed the brain to make better use of its resources–increased attention and better encoding processes that get experiences into memory. The study design was cautious to test more than short-lasting alertness. The memory task was given three days later and not immediately after the intervention so that the researchers could explore the impact on robust memory formation not just transient attentional enhancement. This longer-lasting benefit is what makes the findings relevant to real life. Most people cannot simply take a ninety-minute nap following the insomniacs’ typical wasted night.
Shift workers, new mums, students writing finals, businessmen racing against the clock have no choice but to carry on. Short sharp aerobic activity may be an accessible option for them. The authors highlight that this should not be taken to imply that physical activity can compensate for sleep. Sleep is still necessary for general brain health, emotional regulation and long-term cognitive ability.
Yet, the current findings suggest that when sleep deprivation is not possible, a 20-minute bout of mild to intense exercise can act as a safeguard for one of the brain’s most valued systems. These findings are straightforward in their implications. A few minutes of a bike ride, a walk, or other intervention involving aerobic exercise post-sleep deprivation may be enough to enhance the consolidation of information into memory.