
When it comes to sharpening your memory or improving focus, you might think of brain-boosting supplements, a clean diet, or regular workouts. But one of the most powerful—and most overlooked—tools for enhancing your cognitive performance could be hiding in plain sight: your thermostat. That’s right—your home’s temperature control may be silently helping or hindering your brainpower. What does science say about how your mental clarity reacts to heatwaves, cold snaps, and even post-workout sweats? You’re about to find out.
Key Takeaways
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Brain on Heat: High temperatures impair memory, focus, and reaction time—especially during and after heatwaves without AC.
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Chilling Effects: Cold exposure also lowers mental performance, likely due to reduced brain blood flow and body temperature.
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Performance Boosters: Tyrosine and caffeine may help counteract the negative cognitive effects of both heat and cold.
Temperature Ups and Downs
Research shows that being too hot or too cold messes with your brain in important ways that impair your intellectual capacity. For instance, studies have found that in the summer, people who don’t have or use air conditioning do worse on tests of mental function than folks who keep cool with AC. And when researchers at Harvard looked at how 44 people coped with a heat wave in Boston, they found that the twenty who lived in a dorm without air conditioning had significantly more trouble with cognitive tests than did the twenty-four who lived in cool, temperature-controlled buildings.1 The researchers report that the people living in the heat did worse in five measures of cognitive function including their reaction times, their working memory, their ability to focus on what they were doing and their learning ability.End of the Heat Wave Saw Biggest Difference in Mental Function
The Harvard scientists also point out that the biggest difference in mental performance between the non-AC people and the ones in air conditioning occurred after the heat wave started to end, because in the un-airconditioned setting, the indoor temperatures remained significantly higher than in the cooled facility. They say this happened because the buildings in Massachusetts where the test was done are designed to retain heat in order to cope with the region’s cold winters. They aren’t designed to cool off quickly in the summer. Another study, this one at the University of Pittsburgh, shows that if you do an exercise that’s intense enough to make you sweat heavily, your mental performance also suffers. But in this test, the intellectual drop didn’t occur until an hour or two after the exercise session.2 It sounds like a heavy workout is not a good idea hours before a demanding mental task.Cold Takes a Toll, Too
Cold temperatures can also be a brain problem. In a study at Kent State University, men who were exposed to colder temperatures at various times during the day – down to around 50 degrees – and then warmed up, had problems performing well on mental tasks both while they were chilled and after they had warmed up.3 The Kent State scientists believe that when you are feeling chilly, your brain might actually become colder than the rest of your body. Plus, it’s possible that the cooler temperatures slow the blood supply to your brain as the brain’s blood vessels constrict – and the slowdown can make it harder to concentrate. Of course, the most obvious way to avoid most of these hot and cold related brain problems is to keep your house and workplace at a comfortable temperature. And if you exercise during the day and get hot enough to sweat, don’t schedule important meetings or tasks afterwards.More Tips for Offsetting the Temperature Effect
Two other ways to offset temperature issues, say researchers, are to take tyrosine supplements and caffeine. Supplements of tyrosine, an amino acid, have been shown to “help maintain cognitive function in extreme environmental conditions.”4 One study found that when you’re exposed to hot temperatures, tyrosine protects the brain by maintaining the function of the neurotransmitters dopamine and norepinephrine. And other tests have found a similar benefit in cold temperatures.5 The second tip for mental performance is caffeine. Coffee and tea can support your mental powers when the temperature drops – though I haven’t seen any evidence that it helps during hot weather. But if you’re feeling cold, a test conducted on Navy Seals – who have to maintain a high level of physical and mental performance in challenging conditions – shows that caffeine improves “cognitive function, including vigilance, learning, memory, and mood state.”6 The test on the Seals found that 200 mg of caffeine, the amount in one 12-ounce cup of coffee, was enough to do the trick.Summary
Temperature extremes—whether too hot or too cold—can impair cognitive function, affecting memory, attention, and reaction time. Research shows that maintaining a comfortable indoor climate and using supplements like tyrosine and caffeine can help offset these mental performance dips.
Frequently Asked Questions
How does hot weather affect brain function?
High temperatures reduce cognitive performance, slowing reaction time, memory, and focus—especially without air conditioning.Does cold weather hurt mental performance too?
Yes. Cold temps can constrict brain blood vessels, leading to reduced concentration and slower mental responses.What’s the best temperature for brain function?
Around 70–74°F (21–23°C) is generally considered optimal for comfort and cognitive performance.Can supplements help if I can’t control the temperature?
Yes. Tyrosine supports brain neurotransmitters in hot/cold extremes, and caffeine helps boost alertness, especially in cold conditions.Is it safe to schedule brain-heavy tasks after workouts?
Not always. Intense sweating can impair cognition for up to 2 hours after, so allow time to cool down and recover.Baniassadi, A., Yu, W., Travison, T., Day, R., Lipsitz, L., & Manor, B. (2024). Home Ambient Temperature and Self-reported Attention in Community-Dwelling Older Adults. The Journals of Gerontology: Series A, Biological Sciences and Medical Sciences. https://pubmed.ncbi.nlm.nih.gov/39656181/
Kong LS, Chen D, Zhang JD, Cheng XF, Zhang YL, Li B. The correlation between high temperature and cognitive function: a CHARLS 2018 cross-sectional study. Arch Public Health. 2025 Jul 10;83(1):181. doi: 10.1186/s13690-025-01665-6. PMID: 40635089; PMCID: PMC12243420.https://pmc.ncbi.nlm.nih.gov/articles/PMC12243420/
Sun, C., & Seltenrich, N. (2024). Emerging effects of temperature on human cognition, affect, and health. Progress in Neurobiology, 228, 102711. https://www.sciencedirect.com/science/article/pii/S0301051124000504
Cedeño Laurent, J. G., Williams, A., Oulhote, Y., Zanobetti, A., Allen, J. G., & Spengler, J. D. (2018). Reduced cognitive function during a heat wave among residents of non-air-conditioned buildings: An observational study of young adults in the summer of 2016. PLoS Medicine, 15(7), e1002605. https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002605
Morley J, Beauchamp G, Suyama J, Guyette FX, Reis SE, Callaway CW, Hostler D. Cognitive function following treadmill exercise in thermal protective clothing. Eur J Appl Physiol. 2012 May;112(5):1733-40. doi: 10.1007/s00421-011-2144-4. Epub 2011 Sep 3. PMID: 21892644. https://www.ncbi.nlm.nih.gov/pubmed/21892644/
Ergonomics
. Author manuscript; available in PMC: 2013 Jul 1. Published in final edited form as: Ergonomics. 2012 Apr 16;55(7):792–798. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3375336/
Taylor L, Watkins SL, Marshall H, Dascombe BJ, Foster J. The Impact of Different Environmental Conditions on Cognitive Function: A Focused Review. Front Physiol. 2016 Jan 6;6:372. doi: 10.3389/fphys.2015.00372. PMID: 26779029; PMCID: PMC4701920. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4701920/
O'Brien C, Mahoney C, Tharion WJ, Sils IV, Castellani JW. Dietary tyrosine benefits cognitive and psychomotor performance during body cooling. Physiol Behav. 2007 Feb 28;90(2-3):301-7. doi: 10.1016/j.physbeh.2006.09.027. Epub 2006 Oct 31. PMID: 17078981. https://www.ncbi.nlm.nih.gov/pubmed/17078981
Lieberman HR, Tharion WJ, Shukitt-Hale B, Speckman KL, Tulley R. Effects of caffeine, sleep loss, and stress on cognitive performance and mood during U.S. Navy SEAL training. Sea-Air-Land. Psychopharmacology (Berl). 2002 Nov;164(3):250-61. doi: 10.1007/s00213-002-1217-9. Epub 2002 Sep 5. PMID: 12424548. https://www.ncbi.nlm.nih.gov/pubmed/12424548/