The Gap in Thermal Wellness Research
Most sauna research has been conducted on men. The landmark University of Eastern Finland studies that established the cardiovascular benefits of regular sauna use followed male participants. This is not unusual in exercise and thermal physiology - female hormonal cycles introduce variables that make study design more complex, so researchers have historically defaulted to male subjects.
The result is a significant gap. Women make up a large and growing portion of the thermal wellness community, and the standard protocols rarely account for the physiological reality that thermoregulation changes meaningfully across the menstrual cycle.
This guide covers what we know, where the evidence is strong, and how to apply it practically.
How Your Cycle Affects Thermoregulation
The menstrual cycle involves cyclical changes in estrogen and progesterone that directly affect your body’s ability to regulate temperature.
Follicular phase (Days 1-14, roughly): Estrogen is the dominant hormone. Core body temperature is at its baseline - typically 0.3-0.5°C lower than during the luteal phase. Vasodilation is more efficient, meaning your body is better at moving heat from the core to the skin for dissipation. Sweat onset occurs at a lower core temperature. In practical terms, you tolerate heat better during this phase.
Ovulation (around Day 14): The shift from estrogen dominance to progesterone dominance begins. Some women notice a brief dip in heat tolerance around ovulation itself, though this varies considerably.
Luteal phase (Days 15-28, roughly): Progesterone raises your basal core temperature by 0.3-0.5°C. Your thermoregulatory set point shifts upward. Sweating begins at a higher core temperature, and vasodilation is less efficient. The practical effect: the same sauna session that felt manageable during the follicular phase may feel significantly harder during the luteal phase. You are not less fit or less tough - your physiology has literally changed the thermostat.
Menstruation (Days 1-5): Core temperature returns to baseline as progesterone drops. Many women report that heat tolerance improves quickly once menstruation begins.
Practical Implications for Sauna Practice
This does not mean you should avoid the sauna during the luteal phase. It means you should adjust expectations and potentially modify your protocol.
During the follicular phase: This is your window for pushing intensity if progression is your goal. Higher temperatures, longer sessions, and additional rounds are better tolerated. If you are testing a new protocol or increasing heat exposure, schedule it here.
During the luteal phase: Reduce session duration by 10-20%, lower the temperature by 3-5°C, or reduce the number of rounds. If you normally do two rounds at 85°C, try two rounds at 80°C, or one round at your usual temperature. Listen to your body more carefully during this phase - the signals that indicate you are approaching your limit may arrive sooner.
During menstruation: Return to your normal protocol as comfort allows. Some women find sauna use during menstruation helps with cramp relief, likely due to the vasodilation and muscle relaxation effects of heat. Others prefer to rest. Both are valid responses.
What to Track
If you are already tracking your cycle (via an app, basal body temperature, or wearable), add sauna-specific notes:
- Subjective heat tolerance (1-5 scale) at each session, alongside your cycle day
- HRV response the morning after sauna sessions, correlated with cycle phase
- Session modifications you made (shorter duration, lower temperature) and why
After three to four cycles of tracking, patterns will emerge. You may find that your heat tolerance drops predictably around Day 20, or that your HRV recovery is slower during the luteal phase. This data lets you build a protocol that works with your physiology rather than ignoring it.
A Note on Hormonal Contraception
Hormonal contraceptives (combined pill, progesterone-only pill, hormonal IUD, implant) alter the natural hormonal fluctuations described above. Women on combined oral contraceptives may experience a more blunted thermoregulatory cycle, since the exogenous hormones override the natural estrogen-progesterone oscillation.
If you are on hormonal contraception, the cycle-based timing recommendations above may be less relevant. Track your subjective heat tolerance regardless - you may still notice patterns, even if they do not align neatly with a textbook cycle.
The Bigger Picture
Accounting for the menstrual cycle in sauna practice is not about limitation - it is about precision. The same principle applies in athletic training: female athletes who periodize their training around their cycle consistently outperform those who ignore it. Thermal practice is no different.
The research in this specific area is still emerging, and much of what we know is extrapolated from exercise thermoregulation studies rather than sauna-specific trials. As more women track and share their thermal data, the protocols will improve. For now, the best approach is to combine the existing science with your own observations and adjust accordingly.