Yes, sauna use does increase growth hormone levels. A single 15-minute session in a Finnish sauna at around 72°C (162°F) can roughly double circulating growth hormone, raising levels from about 2 to 5 micrograms per liter within 30 minutes. The effect is real and consistently documented, but as with most things in biology, the practical implications are more nuanced than the headline suggests.
How Heat Triggers Growth Hormone Release
Your brain’s hypothalamus acts as a thermostat for more than just temperature. When your core body temperature rises in a sauna, the hypothalamus releases a signaling molecule called growth hormone-releasing hormone (GHRH), which tells the pituitary gland to pump out growth hormone. This is fundamentally a stress response: the body detects an environmental challenge and mobilizes hormones to help cope with it.
The system has a built-in brake. As growth hormone levels climb, the hypothalamus releases a second signal, somatostatin, which shuts down further growth hormone secretion and makes the pituitary less responsive to additional stimulation. This negative feedback loop is why back-to-back sauna sessions on the same day produce diminishing returns. The pituitary essentially becomes temporarily unresponsive to repeated heat exposure, much the same way it does after repeated bouts of exercise.
How Large Is the Increase?
The most commonly cited figure is a 2- to 2.5-fold increase after a standard Finnish sauna session. In younger men, 15 minutes at 72°C raised growth hormone from a baseline of about 2 micrograms per liter to roughly 5 micrograms per liter, a statistically significant jump that peaked around 30 minutes after the session began.
Studies in women have found similar patterns. Research involving 20 women who completed either 30-minute or 45-minute sauna sessions over two weeks found significant increases in growth hormone alongside rises in cortisol and adrenocorticotropic hormone (ACTH). Prolactin, another pituitary hormone, tends to spike even more dramatically during sauna use, rising 2- to 10-fold across most studies.
The magnitude of the growth hormone response depends on how hot the sauna is, how long you stay, and your baseline hormone levels. Higher temperatures and longer sessions produce larger spikes, though comfort and safety set practical limits. Age matters too: younger adults generally produce a stronger growth hormone response to any stimulus, including heat.
Finnish Sauna vs. Infrared Sauna
Both traditional Finnish saunas (which heat the air to 80–100°C) and infrared saunas (which use radiant heat at lower air temperatures) have been shown to increase growth hormone levels. A systematic review published in Evidence-based Complementary and Alternative Medicine found that increased serum growth hormone was documented after regular sessions with both sauna types.
That said, the existing research isn’t detailed enough to declare one type superior for hormone stimulation. The review’s authors noted there isn’t yet enough evidence to distinguish particular health differences between Finnish-style and infrared sauna bathing. Most of the foundational hormone studies used traditional Finnish saunas, so the strongest data sits there. Infrared saunas achieve lower air temperatures but can still raise core body temperature meaningfully, which is the actual trigger for the hormonal response.
Does the Spike Actually Build Muscle?
This is where enthusiasm should meet realism. The growth hormone increase from a sauna session is transient, typically resolving within an hour or two as the feedback loop restores baseline levels. The question is whether these brief pulses are large enough and frequent enough to drive measurable changes in body composition.
A 2025 study published in Frontiers in Sports and Active Living tested this directly. Researchers had participants complete six weeks of resistance training, with one group adding infrared sauna sessions after each workout. Both groups gained lower-body muscle mass, but the sauna group showed no additional hypertrophy compared to the training-only group. The conclusion was straightforward: incorporating post-exercise sauna bathing does not significantly impact muscle growth.
This aligns with a broader pattern in the research. While animal studies and some cell-level work suggest that heat exposure activates muscle growth pathways (including heat-shock proteins and the mTOR signaling cascade), human studies have produced mixed results. Some have found increased muscle fiber size with passive heating; others have found no change. Regular post-exercise sauna or hot water immersion does not appear to increase lean mass in athletes beyond what training alone provides.
The disconnect makes biological sense. Growth hormone injections used clinically deliver sustained, supraphysiological doses over weeks or months. A sauna-induced spike that doubles your growth hormone for an hour is a fundamentally different signal to your tissues. It’s a bit like the difference between a brief rain shower and an irrigation system: both involve water, but only one reliably grows crops.
What About Fat Loss?
One study found that three weeks of post-exercise sauna bathing in extreme heat (100°C) reduced body mass and fat mass. However, most studies investigating regular use of traditional saunas or hot water immersion have found no additional fat loss benefits from heat exposure. The weight you lose during a sauna session is almost entirely water, and it returns as soon as you rehydrate.
Other Hormonal Effects Worth Knowing
Growth hormone isn’t the only hormone that responds to sauna use. Cortisol, the body’s primary stress hormone, increases 1.5- to 3-fold during a sauna session in most studies. Interestingly, repeated sauna use over time appears to blunt this cortisol response, suggesting the body adapts to the heat stress. Regular sauna bathers show significantly lower cortisol concentrations compared to their early sessions.
Testosterone levels, a common concern for people interested in sauna and muscle growth, do not appear to change meaningfully during sauna bathing. Multiple studies have found no significant shifts in testosterone, DHEA-S (a testosterone precursor), or prolactin with repeated sauna use. So while the acute hormonal response to a single session is broad, the chronic adaptations are more selective.
Practical Takeaways for Sauna Use
If your primary goal is maximizing the growth hormone response from a sauna session, the research points to a few practical guidelines:
- Temperature: Traditional Finnish saunas at 72–100°C produce the most well-documented hormonal responses. Infrared saunas likely work too, but the evidence is thinner.
- Duration: Sessions of 15 to 30 minutes are sufficient to trigger a significant spike. Longer sessions may produce larger increases, but with diminishing returns and greater strain on your cardiovascular system.
- Timing: Because somatostatin feedback reduces the pituitary’s responsiveness, spacing sauna sessions at least several hours apart (or limiting to one per day) is more effective than back-to-back rounds for growth hormone purposes.
- Expectations: The growth hormone increase is real, reproducible, and biologically interesting. But it is brief, and the current evidence does not support the claim that sauna-induced growth hormone spikes translate into meaningful muscle gain or fat loss beyond what exercise alone provides.
Sauna bathing has well-documented benefits for cardiovascular health, stress reduction, and recovery. The growth hormone response is a genuine physiological effect, just not the muscle-building shortcut it’s sometimes marketed as.