What We Are Reading This Quarter
Every quarter, we review newly published peer-reviewed research on thermal exposure, sauna use, and heat-based interventions. Here are the papers that caught our attention in early 2026, with plain-language summaries of what they found and what it means for practice.
Sauna Frequency and Inflammatory Markers in Middle-Aged Adults
Published in: European Journal of Preventive Cardiology, January 2026
A Finnish cohort study followed 1,847 middle-aged adults (42% female) over 18 months, comparing those who used a sauna 2-3 times per week with those who used it 4-7 times per week. The higher-frequency group showed statistically significant reductions in C-reactive protein (CRP) and interleukin-6 (IL-6) - two key markers of systemic inflammation - after adjusting for age, BMI, physical activity, and alcohol consumption.
The takeaway: This adds to the growing body of evidence that sauna frequency matters. The dose-response relationship between sauna use and inflammatory markers appears to be real, with 4+ sessions per week consistently outperforming lower frequencies in observational data. The limitation, as always with cohort studies, is that correlation does not establish causation - people who sauna more frequently may differ from those who do not in ways the adjustment variables do not capture.
Post-Exercise Cold Water Immersion and Muscle Protein Synthesis: A Dose-Response Analysis
Published in: Journal of Applied Physiology, February 2026
Researchers at the Australian Institute of Sport conducted a randomized controlled trial with 48 resistance-trained men, comparing muscle protein synthesis rates over 48 hours after a standardized lower-body strength session. Participants were assigned to one of four conditions: no cold exposure, 5 minutes at 10°C, 10 minutes at 10°C, or 15 minutes at 10°C, all administered within 15 minutes post-exercise.
The 10-minute and 15-minute groups showed a 17% and 24% reduction in myofibrillar protein synthesis, respectively. The 5-minute group showed no statistically significant difference from control.
The takeaway: This refines our understanding of the cold-after-strength debate. Brief cold exposure (under 5 minutes) may not meaningfully interfere with muscle adaptation, while extended immersion likely does. If you want both cold exposure and hypertrophy, keep the cold brief on lifting days or separate them by at least 6 hours.
Dry Sauna Exposure and Sleep Architecture in Adults with Insomnia Symptoms
Published in: Sleep Medicine, January 2026
A small but well-designed crossover study (n=32, 56% female) examined the effect of a single 20-minute dry sauna session at 80°C, completed 90 minutes before bedtime, on polysomnography-measured sleep architecture. Compared to control nights, sauna nights showed a 12% increase in slow-wave sleep (deep sleep) duration and a reduction in sleep-onset latency by an average of 11 minutes. Effects were more pronounced in participants over 50.
The takeaway: This is one of the first studies to use full polysomnography rather than wearable-derived sleep scores to assess sauna’s effect on sleep. The increase in slow-wave sleep is particularly interesting - this is the sleep stage most associated with physical recovery and memory consolidation, and it is the stage that declines most with age. The 90-minute buffer between sauna and bed appears to be a practical minimum for allowing core temperature to begin its descent, which is the physiological trigger for sleep onset.
Why This Matters
None of these studies alone should change your protocol overnight. But taken together, they reinforce several principles we build on at HeatLore: frequency matters more than intensity for systemic health benefits, cold exposure timing relative to training requires precision, and evening sauna use - timed correctly - may be one of the most accessible tools for improving sleep quality.
We will be back next quarter with more. If you come across a paper you think we should cover, send it our way.