Physical activity during the day may help memory work better the next morning. That is the conclusion researchers from University College London and the University of Oxford reached after studying how movement, sedentary behavior, and sleep relate to brain function. The most interesting finding did not appear right after a workout, but several hours later — after a person had gone to bed and woken up.
Memory Turned Out to Be Linked to How the Previous Day Went
The study involved 76 healthy people aged 50 to 83. For eight days they wore special devices that tracked physical activity and sleep around the clock. Each day participants also took computer tests measuring memory, attention, reaction speed, and other cognitive functions.
Scientists found that on days following higher physical activity, participants on average performed better on some memory tests. An extra 30 minutes of moderate or vigorous activity was associated with roughly a 0.16 standard-deviation improvement in working memory scores and a 0.15 improvement in episodic memory.
There is a flip side. An additional half hour spent mostly sitting was linked to a slight decline in working-memory test scores.
That does not mean a 30-minute walk will automatically turn someone into a genius the next day. The study shows a statistical association, not proof that exercise itself caused the memory improvement. The observation lasted only eight days, and the sample was small.
What About Sleep
Here is where it gets most interesting. Physical activity did not replace a good night’s sleep.
Longer sleep was associated with better scores on episodic-memory and psychomotor-speed tests. Researchers also found links between the amount of individual sleep stages and some cognitive measures: more slow-wave sleep corresponded to better episodic memory, while extra REM sleep was linked to better attention.
The picture is fairly simple: the brain may care both about how much a person moved during the day and how they slept at night. And the influence of these factors does not necessarily come down to a single mechanism.
Why Yesterday’s Activity Might Matter Today
Physical activity affects the cardiovascular system, metabolism, and many processes tied to brain function. But in this specific study, researchers cannot say the effect was explained by, for example, increased blood flow or a rise in any one neurotransmitter.
That is part of what makes the research interesting: scientists found an association that persisted into the next day, but they did not turn it into a ready-made recipe for better memory.
The broader picture still looks convincing: regular physical activity has long been considered an important part of a healthy lifestyle. The World Health Organization recommends that adults get at least 150 minutes of moderate activity per week or 75 minutes of vigorous activity. Yet about 31% of adults worldwide — roughly 1.8 billion people — did not reach that level in 2022. If current trends continue, the share of insufficiently active adults could rise to 35% by 2030.
So before a demanding day, it is worth paying attention not only to the alarm clock and bedtime. What happens to the body during daylight hours may also shape how alert and focused the brain feels in the morning.
And the brain seems to have one unpleasant habit: it can send the bill for yesterday’s lifestyle today.
