Sleep disturbances affect an estimated 50-70 million adults in the US alone, with significant implications for mental health, cognitive function, and overall well-being. While cognitive behavioural therapy for insomnia (CBT-I) remains the gold standard treatment, researchers are increasingly exploring complementary approaches (including an ancient practice now backed by modern science: heat therapy.
The thermoregulation-sleep connection
Sleep onset is intimately connected to body temperature. As evening approaches, core body temperature naturally begins to decline: a process regulated by the circadian system. This drop signals the brain to initiate sleep processes, including melatonin release.
But chronic stress disrupts this system. Elevated cortisol keeps the body in a state of hyperarousal, interfering with the natural temperature decline. The result is a common complaint among those with anxiety and stress-related conditions: feeling “tired but wired” at bedtime.
Heat therapy offers a counterintuitive solution. By artificially raising body temperature through external heat exposure, we can trigger a more pronounced compensatory cooling response afterward. This accelerated temperature drop appears to enhance sleep onset and improve sleep efficiency.
What the research shows
A 2019 systematic review and meta-analysis published in Sleep Medicine Reviews examined 13 studies on passive body heating before sleep. The findings were notable: heating protocols initiated 1-2 hours before bedtime significantly improved both sleep onset latency (time to fall asleep) and subjective sleep quality.
The mechanisms appear to involve multiple pathways:
- Autonomic regulation: Heat exposure shifts the nervous system toward parasympathetic dominance, reducing the hyperarousal associated with insomnia.
- Muscle relaxation: Thermal therapy reduces muscle tension, addressing the physical manifestations of stress that interfere with sleep.
- Endorphin release: Heat stress triggers endogenous opioid production, promoting relaxation and positive mood states.
- Cortisol modulation: Regular heat therapy practice appears to improve HPA axis regulation over time.
Infrared sauna applications
Among heat therapy modalities, infrared saunas have gained particular attention. Unlike conventional saunas that heat ambient air to extreme temperatures, infrared technology warms the body directly through radiant heat. This allows for therapeutic effects at more tolerable temperatures; typically 120–140°F compared to 180°F+ in traditional saunas.
For individuals with anxiety or sensory sensitivities, the gentler infrared environment may be more accessible. The private nature of most infrared sauna for sleep sessions also eliminates social stressors that might otherwise counteract relaxation benefits.
Clinical considerations
Heat therapy should be viewed as a complementary approach rather than a replacement for evidence-based treatments. For individuals with clinical insomnia, anxiety disorders, or depression, established interventions remain primary.
But as part of a comprehensive sleep hygiene protocol, scheduled heat exposure may offer meaningful benefits; particularly for those whose sleep difficulties are stress-related. The ritual aspect of a regular heat therapy practice may also provide psychological benefits through routine and intentional self-care.
As our understanding of the body-mind connection deepens, interventions that address physiological pathways to psychological wellbeing deserve continued attention. Heat therapy represents one such bridge between ancient wisdom and modern science.
Tim Williamson, a psychology graduate from the University of Hertfordshire, has a keen interest in the fields of mental health, wellness, and lifestyle.
