That feeling of deep relaxation after soaking in a hot tub or enjoying a sauna session isn’t just in your imagination—it’s backed by science. Research shows that heat therapy can significantly affect your brain and nervous system, producing measurable changes that improve your mental wellbeing.

At Great Bay Spa & Sauna, we’re fascinated by the growing body of research suggesting that regular sessions in hot tubs and saunas can have profound effects on brain function, mood, and overall mental health. Let’s dive into what science tells us about this connection.

The “Totonou” State: Understanding Deep Relaxation

Researchers in Japan have identified a unique state of well-being achieved through alternating hot sauna sessions with cold water immersion, known as the “totonou” state. A 2023 study published in PLOS One examined this phenomenon, finding that when participants followed a cycle of hot sauna (85-90°C), cold water bath (16°C), and rest, they experienced significant neural changes.

The brain scans revealed increased theta and alpha wave activity—patterns associated with deep relaxation, meditation, and enhanced cognitive function. Participants reported feelings of “boundless pleasure,” mental clarity, and a unique sense of physical and mental restoration. This state isn’t just subjective—researchers could actually measure these changes in brain activity.

Brain Wave Benefits: How Heat Therapy Changes Neural Activity

The science behind heat therapy is fascinating. When you soak in a hot tub or use a sauna, researchers have observed:

  • Increased theta waves: Associated with deep relaxation, creativity, and emotional processing
  • Enhanced alpha wave activity: Linked to relaxation, stress reduction, and mental clarity
  • Improved auditory processing: Studies show better pre-attentive auditory processing after sauna use
  • Faster reaction times: Participants completed cognitive tasks more quickly after sauna sessions

These changes in brain activity help explain why you feel mentally clearer and more focused after using a hot tub or sauna. The science suggests that heat therapy puts your brain in a more efficient operational state.

Two people sipping coffee in a hot tub.

Improved Cardiovascular Health Means Better Brain Function

Your brain depends on good blood flow, and this is where hot tubs and saunas excel. A 2018 study published in the medical journal Neurology found that frequent sauna use was associated with a significantly reduced risk of stroke. Participants who used saunas 4-7 times per week were 60% less likely to suffer a stroke than those who used them only once weekly.

How does this work? Heat therapy:

  • Widens blood vessels (vasodilation)
  • Temporarily lowers blood pressure
  • Improves overall cardiovascular function
  • Enhances blood flow to the brain

These cardiovascular benefits ensure your brain receives optimal oxygen and nutrients, supporting cognitive function and protecting against deterioration.

Stress Reduction and Mental Clarity

One of the most immediate benefits of hot tub or sauna use is stress reduction. When you immerse yourself in warm water or heated air, your body responds by:

  • Decreasing cortisol (the stress hormone) levels
  • Releasing endorphins and other feel-good neurotransmitters
  • Activating the parasympathetic nervous system (your “rest and digest” mode)
  • Reducing muscle tension, which signals safety to your brain

These physiological changes create a powerful feedback loop, telling your brain it’s safe to relax and disengage from stress-response patterns. Many users report that creative solutions to problems often emerge during or after heat therapy sessions, when the mind is calm and clear.

Better Sleep Through Temperature Regulation

Quality sleep is essential for brain health, and both hot tubs and saunas can help establish healthy sleep patterns. Research shows that an evening soak in a hot tub 90 minutes before bedtime can:

  • Trigger a natural drop in body temperature that signals sleep readiness
  • Relax tense muscles that might otherwise interfere with comfort during sleep
  • Reduce anxiety and racing thoughts that often delay sleep onset
  • Improve overall sleep quality by promoting deeper, more restorative sleep stages

Cleveland Clinic researchers note that this temperature change encourages better quality sleep, with many users reporting less difficulty falling asleep and fewer nighttime awakenings.

Physical Benefits That Support Mental Wellness

The mind-body connection means that physical comfort often translates to mental ease. Hot tubs and saunas provide:

  • Pain relief from chronic conditions, which reduces mental distress
  • Muscle relaxation that decreases physical tension
  • Buoyancy in hot tubs that relieves pressure on joints
  • Improved circulation that supports whole-body wellness

When your body feels good, your mind can relax—it’s that simple. Many hot tub and sauna users report that their anxiety and depression symptoms ease during regular heat therapy.

Experience the Brain Benefits at Great Bay Spa & Sauna

At Great Bay Spa & Sauna, we’re committed to helping our New England customers experience the scientifically-backed benefits of heat therapy. Whether you’re looking for stress relief, improved sleep, enhanced cognition, or simply a way to relax deeply, we have the perfect hot tub or sauna solution for your needs.

Our experts can help you choose the right model and establish a routine that maximizes these brain benefits. Contact us today to learn more about how our products can support not just your physical comfort, but your mental wellbeing too!