How Today’s Exercise and Sleep Shape Your Brain Performance Tomorrow
This Week’s Research Highlight
Understanding the Brain’s Daily Rhythm
Have you noticed how some days your mind feels razor-sharp, but on other days even simple tasks seem to require extra effort?
The difference might just lie in what you did yesterday — particularly how you moved and how you slept.
Scientists have long recognized that physical activity can boost our mental performance in multiple ways. In the short term, exercise can deliver an immediate cognitive boost — that shot of mental clarity that some people might experience right after a workout.
Meanwhile, over the course of months and years, physiological adaptations accrued from regular physical activity help build and maintain the brain's infrastructure — supporting memory and complex thinking abilities.
But there's an intriguing middle ground that is less well understood: how does physical activity influence mental performance the following day? In other words, could going for a run today help set you up for success at work or at school tomorrow?
And on the opposite end of the equation, how does the lack of physical activity (i.e., sedentary behavior) affect next-day cognition? Does prolonged sitting take a toll on your brainpower over a 24-hour cycle?
Finally, we know that exercise can influence sleep, both in terms of duration and quality. If indeed physical activity improves brainpower the next day, to what extent can this be explained by changes in sleep?
A new study offers useful insights into all of these questions.
Inside the Study
To answer these questions, researchers needed to track both physical activity and cognitive performance with unprecedented precision.
To that end, the team recruited 76 British adults aged 50-83 years to participate in an 8-day study. Each participant wore a specialized wrist device that measured their physical activity levels and sleep patterns around the clock.
These devices continuously tracked different intensities of physical activity (light and moderate-to-vigorous activity), sedentary time, sleep time, and even different stages of sleep using advanced machine learning algorithms.
Every day, participants completed online cognitive tests which measured various mental abilities:
- Attention (ability to focus and identify specific information)
- Episodic memory (remembering specific events or information)
- Working memory (holding and manipulating short-term information in your head, like keeping a phone number in mind while looking for your keys)
- Psychomotor speed (reaction time)
- Executive function (complex thinking and decision-making)
In this way, researchers could capture how physical activity and sleep patterns on one day might influence mental performance the following day — and figure out whether these effects were independent of one another.
How Exercise Shapes Tomorrow’s Thinking
Let's start with the results related to physical activity. The study found that adding just 30 minutes of moderate physical activity significantly improved both episodic and working memory. These improvements in memory reflect specific biological processes occurring in the brain.
Physical activity triggers both immediate and sustained changes in brain function through several key pathways. During moderate-to-vigorous exercise, cerebral blood flow increases by around 20%, delivering oxygen and glucose to neural tissues. This elevated blood flow persists for several hours post-exercise, through a process called post-exercise hyperperfusion.
During exercise, the brain undergoes an orchestrated release of neurotransmitters — the chemical messengers that facilitate neural communication. These include dopamine, which modulates attention and reward pathways, and norepinephrine, which enhances alertness and memory formation by strengthening synaptic connections.
Finally, physical activity increases the production of brain-derived neurotrophic factor (BDNF), a protein that supports neuroplasticity — the brain's ability to form and strengthen neural connections. BDNF levels can remain elevated for up to 48 hours after exercise, no doubt contributing to the improved memory performance observed in the study the following day.
The Cognitive Cost of Sitting
While exercise boots brain power, sitting does the opposite – and the effects last longer than you might think. Every additional 30 minutes spent being sedentary was associated with a decline in working memory performance the next day.
Sitting for extended periods reduces blood flow to the brain, particularly in regions crucial for complex thinking and decision-making. When we sit for long periods, blood tends to pool in our lower body, decreasing the volume reaching our brain. This reduced cerebral blood flow particularly affects the prefrontal cortex, a brain region we rely on for tasks requiring focused attention and mental flexibility.
Prolonged sitting also affects how our brain uses glucose, its primary energy source. When we remain sedentary, our muscles become less efficient at processing glucose, leading to higher blood sugar levels. This doesn't just affect our muscles, it also impacts how brain tissue metabolizes glucose. Our brain cells become less responsive to insulin, the hormone that helps them absorb glucose, making it harder for them to access the energy they need to fire one all cylinders.
This helps explain why taking regular movement breaks during long periods of sitting isn't just good for our bodies — it's essential for maintaining sharp mental performance throughout the day.
Your Brain’s Nightly Restoration
Unsurprisingly, sleep also emerged as a powerful influence on next-day cognitive performance. Compared to those who slept less than six hours, participants who got at least six hours of sleep showed significant improvements in episodic memory, psychomotor speed (reaction time), and attention scores.
Beyond sleep duration, sleep quality was also key for cognitive performance. Each additional 30 minutes spent in REM sleep was associated with better attention the next day. Meanwhile, an extra 30 minutes of slow-wave sleep boosted episodic memory scores.
"Independent of moderate-to-vigorous physical activity on the previous day, sleep duration ≥ 6 hours (compared with < 6 hours) on the previous night was associated with episodic memory scores 0.60 SD higher and psychomotor speed 0.34 SD faster."
During sleep, our brains don't simply shut down — they engage in essential maintenance and processing work. Different sleep stages serve distinct purposes in supporting cognitive function.
During slow-wave sleep (our deepest sleep stage), the brain goes through a crucial cleaning process. The interstitial space between brain cells expands by up to 60%, creating channels that efficiently clear metabolic waste products that accumulate during wakefulness.
This stage is also when the brain consolidates memories, transferring information from short-term to long-term storage — like saving files from a computer's temporary memory to its hard drive. This explains why the study found that more time in slow-wave sleep led to better memory performance the next day.
REM sleep serves different but equally important functions. During this stage, the brain processes emotional information and strengthens neural pathways involved in learning and attention. The brain also rehearses and integrates new information with existing knowledge networks during REM sleep.
All of this, taken together, would explain why additional REM sleep improved attention scores in these participants.
How Exercise and Sleep Work Together (and Apart)
As we alluded to earlier, physical activity can influence cognitive function indirectly through its interaction with sleep.
When we exercise, our body temperature temporarily rises, and then rebounds back down in the hours afterward. This natural cooling process helps trigger sleep onset.
Exercise also increases levels of adenosine in our brain. Adenosine naturally builds up throughout our waking hours, creating what sleep scientists refer to as "sleep pressure" — that feeling of sleepiness that builds the longer we stay awake. Physical activity accelerates this process, making us more likely to sink into deep, restorative sleep when bedtime arrives.
Additionally, exercise helps regulate our internal biological clock, or circadian rhythm. When we're physically active (especially outdoors), we expose ourselves to natural light and establish clear patterns of activity and rest. This exposure, combined with the physical exertion itself, helps synchronize our body's internal clock with the natural day-night cycle.
However, in this study, the researchers found that physical activity and sleep quality boost cognitive performance independently of each other. When researchers adjusted their analysis to account for sleep, the benefits of physical activity largely remained unchanged.
Breaking the Sedentary Cycle
Both physical activity and quality sleep independently contribute to cognitive performance. This means we need to attend to both factors — we can't simply make up for a sedentary day by sleeping longer, or compensate for poor sleep with extra exercise. Instead, success lies in creating daily routines that support both movement and rest.
Extended periods of sitting can compromise your mental performance the next day, even if you get a good night's sleep. This is where InTUNE Training (Integrative and Opportunistic Training) can make a difference.
We developed InTUNE specifically to help people integrate movement throughout their workday. InTUNE encourages accumulating activity through short, bodyweight movement breaks that naturally align with your work rhythm. You might do a few exercises between tasks, after sending an email, or before starting a meeting. This approach serves multiple purposes: it reduces extended sedentary periods, increases total daily activity, and potentially boosts cognitive function at key moments.
Practical Steps for Better Brain Performance
- Break up sedentary time: Use the InTUNE approach to incorporate brief movement sessions throughout your day. Even simple bodyweight exercises between tasks can help maintain cognitive function.
- Ensure plenty of physical activity: Aim for at least 30 minutes of moderate physical activity daily — this could be accumulated through multiple shorter sessions rather than one longer workout.
- Protect your sleep: Make getting at least six hours of sleep a priority. The research shows this is a crucial threshold for cognitive benefits.
- Create movement triggers: Look for natural cues in your day that can serve as reminders to move — finishing a task, ending a meeting, or completing an email can all become cues for brief activity.
Random Trivia & Weird News
🏛️ Aristotle's renowned school in Athens got its name from his habit of walking while teaching.
While we're just now elucidating the science behind how movement affects thinking, the ancient Greeks may have intuited this connection over two thousand years ago.
Aristotle's school in Athens was known as the Peripatetic School. This moniker was coined from his tendency to walk around as he taught. “Peripatetic” comes from the Greek word περιπατητικός (peripatētikós), meaning “given to walking around.” Aristotle and his students would stroll through the Lyceum's covered walkways, called peripatoi, engaging in deep philosophical discussions while in motion. This predilection reflected a broader Greek understanding of the link between physical and mental activity. Their gymnasiums weren't just for physical training, but were also centers of intellectual discourse.
Next time you're stuck on a difficult problem, consider going for a walk — you'll be participating in a tradition of combining movement and thinking that dates back to some of history's greatest minds.
Podcasts We Loved This Week
- Marc Hamilton: The second most important muscle in your body and how to train it. Via Siim Land.
- Chandra Reynolds & Ryan Bruellman: 8.5 hours of daily sitting linked to higher BMI and cholesterol. Via Science Friday.
Products We Like
Oura Ring
If you’d like to gain insight into your own daily patterns of movement and sleep, the Oura Ring offers a window into these crucial behaviors.
The ring measures body temperature, heart rate, and movement patterns throughout your day and night, helping you see how your activity levels might influence your sleep quality. It can identify periods of moderate-to-vigorous physical activity, while its sleep tracking capabilities extend to differentiating between REM sleep and deep sleep stages.
Finally, the form factor solves a common problem with sleep tracking: a lot of people (myself included) find wrist-worn devices uncomfortable during sleep. The ring's small size, as well as its 4-7 day battery life, make it super practical for continuous wear, allowing you to build a complete picture of your daily patterns over time.
humanOS Catalog Feature of the Week
Alertness and Task Switching — From Daily Performance and Sleep
To access this lesson…
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- Find the Daily Performance and Sleep Course
- See lesson 04 - Alertness and Task Switching
Or use the search function in the navigation, by typing “Alertness and Task Switching”
This lesson from our Daily Performance Program reveals the startling science behind how sleep affects your cognitive performance.
You'll discover why getting six hours of sleep for nine nights can leave you as mentally impaired as staying awake for two days straight — and why you might not even notice it happening!
Wishing you the best,
