Could a Hot Tub Help Keep Your Brain Sharp as You Age?

When most people think about the benefits of a hot tub, relaxation is probably at the top of the list.

But emerging research from the University of Portsmouth suggests that regular hot-water immersion could have another interesting benefit: it may help support certain aspects of cognitive function in older adults.

New research looks at hot water and the ageing brain

Researchers at the University of Portsmouth have been investigating whether passive heating — raising the body’s temperature through activities such as hot-water immersion rather than exercise — could provide some of the health benefits associated with physical activity.

In an earlier University of Portsmouth research announcement, scientists described a study examining whether regular hot-tub sessions could influence cardiovascular function, muscle function and cognitive abilities in adults aged 55 and over.

The research has now produced encouraging results.

A 2026 study published in Experimental Physiology examined the effects of repeated hot-water immersion on cognitive performance in healthy older adults. Participants completed hot-water immersion sessions in 40°C water for one hour, two to three times a week, over six weeks.

What did the researchers find?

The results suggest that regular hot-water immersion may improve certain areas of cognitive performance.

After the six-week intervention, participants showed improvements in:

• Working memory, measured using a 1-back task
• Logical reasoning

However, the researchers did not find improvements across every cognitive test. Measures of more demanding working memory and reaction-time-based inhibition did not significantly change.

That distinction is important. The findings don’t mean that sitting in a hot tub makes someone universally smarter or prevents cognitive decline. Instead, they suggest that repeated exposure to heat may have a positive effect on specific aspects of cognitive performance.

Why might hot water affect the brain?

One reason researchers are interested in hot-water immersion is that heating the body produces physiological responses that overlap with some of the responses seen during exercise.

Hot-water immersion raises core body temperature and places demands on the cardiovascular system. Researchers have proposed that these changes could potentially influence blood flow and other physiological processes relevant to brain function.

Interestingly, however, the 2026 Portsmouth study did not find that improvements in cognition were explained by a lasting increase in cerebral oxygenation or carotid blood flow. Those findings mean that the precise mechanism behind the cognitive improvements remains uncertain and requires further investigation.

What does this mean for older adults?

The research is particularly interesting because maintaining regular exercise can become more difficult as people get older.

The University of Portsmouth researchers describe passive heating as a potential alternative or complementary approach for people who may struggle to participate in conventional exercise.

That doesn’t mean a hot tub should replace exercise. Physical activity has a much broader evidence base for supporting healthy ageing. Instead, hot-water immersion could eventually prove to be an additional lifestyle activity worth investigating.

For hot-tub owners, the research provides an intriguing reason to think beyond relaxation: regular hot-water sessions may potentially have benefits that extend to cognitive function as well.

The research is promising — but it’s still early

There is an important caveat.

The 2026 study involved only 12 healthy older adults, so the findings need to be confirmed in larger and more diverse groups before we can draw strong conclusions about the wider population.

The study also looked at cognitive performance rather than diagnosing or preventing conditions such as dementia or Alzheimer’s disease. The researchers found no significant changes in the neurodegeneration-related biomarkers they measured over the six-week period.

So, for now, it’s best to view hot-water immersion as an interesting area of healthy-ageing research, rather than a proven treatment for cognitive decline.

A relaxing habit with an interesting potential benefit

The idea that something as enjoyable as relaxing in warm water could also influence aspects of cognitive performance is certainly worth watching.

University of Portsmouth research has found that repeated hot-water immersion was associated with improvements in working memory and logical reasoning in a small group of healthy older adults.

More research is needed to understand exactly why these changes occurred and whether similar benefits would be seen in larger groups over longer periods.

In the meantime, the research adds another fascinating dimension to our understanding of hot-water immersion — and suggests that the benefits of a relaxing soak may extend further than we once thought.

Important: Hot-tub use isn’t suitable for everyone, particularly people with certain cardiovascular or other medical conditions. Anyone with a health condition or concerns about heat exposure should speak with an appropriate healthcare professional before beginning regular hot-tub sessions.