Reviewed by Emily Carter, MSc, RD
Registered Dietitian & Hydration Research Specialist. Emily holds a Master of Science in Human Nutrition and has spent over a decade translating nutrition research into practical, evidence-based guidance for everyday health and athletic performance.
Quick answer: Sauna produces significant hormonal responses — growth hormone elevates by up to 200% above baseline with the two-round protocol, cortisol normalises with regular use, and luteinising hormone (which signals testosterone production) shows acute elevation post-session. The net hormonal effect of regular sauna use supports muscle growth, recovery, fat metabolism, and stress resilience.
The Hormonal Case for Sauna
Hormones govern body composition, energy, recovery, stress response, and reproductive health. Most people optimise their hormones through diet, sleep, and exercise. Sauna is a fourth lever that is underutilised, largely because the hormonal effects are less well-known than the cardiovascular benefits — despite being equally well-documented.
The key hormones affected by sauna are growth hormone, cortisol, and luteinising hormone (LH). Each responds differently, and understanding the timing and mechanism allows you to position sauna strategically in your routine.
Growth Hormone: The Primary Anabolic Signal
Growth hormone (GH) is the most dramatically affected hormone during sauna use. Research by Leppäluoto et al. found that two 20-minute sauna rounds separated by a 30-minute cooling interval elevated growth hormone by up to 200% above baseline. The two-round protocol produces a significantly higher response than a single longer session — the cooling interval appears to reset the GH response, allowing a second peak when heat is reapplied.
Growth hormone drives:
- Muscle protein synthesis — building and repairing muscle tissue between training sessions
- Fat oxidation — stimulating lipolysis (the breakdown of fat stores for energy)
- Tissue repair — accelerating recovery from exercise-induced muscle damage
- Bone density — supporting skeletal integrity, particularly relevant for older adults
For athletes and anyone focused on body composition, the GH response to sauna is a meaningful physiological edge. Post-workout sauna stacks a second GH stimulus on top of the training-induced response, producing a compounded anabolic environment during the recovery window. For the full performance context, see our guide on sauna and athletic performance.
Testosterone: What the Research Actually Shows
Testosterone's relationship with sauna is more nuanced than often portrayed. The acute response is complex: studies show a temporary reduction in testosterone during and immediately after the sauna session (the testes are heat-sensitive and temporarily reduce production in response to elevated scrotal temperature), followed by a rebound elevation in the hours following the session.
The luteinising hormone (LH) response is more consistent — LH elevates acutely post-sauna, which is the pituitary signal for testosterone production. For regular sauna users, the LH elevation may support testosterone production over time, though the research on chronic testosterone levels in sauna users shows mixed results.
The practical implication: do not use sauna immediately before events where you want peak testosterone output (competition, for example). Post-workout sauna is appropriate and does not significantly impair testosterone levels on a meaningful timescale for recreational athletes.
Cortisol: The Stress Hormone That Sauna Normalises
Cortisol is both stress hormone and catabolic signal — in excess, it promotes muscle breakdown, fat storage (particularly visceral fat), impairs immune function, and drives anxiety. Most people under chronic stress have persistently elevated baseline cortisol.
Sauna produces a paradoxical cortisol response: acute sessions briefly elevate cortisol (a stress response to heat), followed by a below-baseline reduction during and after the cool-down phase. According to the Hussain and Cohen 2018 clinical review, regular sauna users show consistently lower resting cortisol levels than matched controls. This chronic cortisol normalisation is one of the key mechanisms behind sauna's mental health, body composition, and recovery benefits.
Lower cortisol means: better muscle preservation during caloric restriction, reduced abdominal fat accumulation, improved sleep quality, and a calmer baseline stress response.
Other Hormonal Effects
Norepinephrine
Norepinephrine — the alertness and focus hormone — elevates significantly during cold plunge and to a lesser degree during sauna itself. For contrast therapy (sauna + cold plunge), the combined norepinephrine response contributes to the post-session state of alert calm that practitioners describe.
Beta-Endorphins
Beta-endorphins — endogenous opioid peptides — elevate during sauna heat stress, producing the pain relief, mood elevation, and reduced anxiety that characterise the post-sauna state. This is the same compound responsible for the "runner's high" — accessible without the physical effort of running.
Prolactin
Prolactin — a hormone involved in immune function and recovery — shows acute elevation post-sauna. The physiological significance for recovery is still being studied, but the elevation is consistent across multiple studies of sauna hormonal response.
The Protocol That Maximises Hormonal Response
| Goal | Protocol | Key Variable |
|---|---|---|
| Maximum GH elevation | 2 × 20 min rounds, 30 min cooling between | Two rounds with cooling interval |
| Cortisol normalisation | 3–4 sessions/week consistently | Frequency over weeks |
| Post-workout anabolic window | Sauna within 30 min of training | Timing relative to training |
| Combined GH + norepinephrine | Sauna then cold plunge, 2–3 rounds | Contrast therapy protocol |
Hydration and Hormonal Response
Dehydration impairs the hormonal response to sauna. Growth hormone secretion requires adequate metabolic function — dehydration blunts the GH peak. Cortisol, conversely, rises in response to dehydration stress, counteracting the normalisation effect you are seeking. Entering a sauna dehydrated produces a session that drives cortisol up rather than normalising it.
Drink 300–500ml before your session. Keep the Mammoth Mug 2.5L accessible between rounds and rehydrate with 500–750ml post-session. For athletes stacking sauna with training, the combined fluid loss from training and sauna is significant — see our guide on sauna dehydration and our resource on post-session rehydration for the full protocol.
- Does Sauna Improve Athletic Performance? What the Research Says
- Does Sauna Help With Muscle Recovery? What the Science Shows
- 7 Sauna Health Benefits Backed by Science
- Sauna Dehydration: How Much Fluid You Lose
- Sauna Rave Toronto: NRG Event Guide
For a complete overview of sauna use, see our beginner guide to sauna.
Frequently Asked Questions
Does sauna boost testosterone?
The testosterone response to sauna is nuanced — testosterone temporarily decreases during the session as heat suppresses testicular function, then rebounds in the hours after. Luteinising hormone (the pituitary signal for testosterone production) shows consistent acute elevation post-sauna. Regular sauna users do not show significantly different chronic testosterone levels than non-users in most studies. The hormonal benefit of sauna for body composition and recovery is driven primarily by growth hormone and cortisol normalisation, not testosterone directly.
How much does sauna increase growth hormone?
The two-round sauna protocol (two 20-minute sessions with a 30-minute cooling interval) produces growth hormone elevations of up to 200% above baseline, according to Leppäluoto et al. This is comparable in magnitude to the GH response from high-intensity interval training. Single longer sessions produce lower GH output than the two-round protocol — the cooling interval between rounds appears to allow a second hormonal peak. For the full performance context, see our sauna athletic performance guide.
Is sauna anabolic or catabolic?
Sauna is net anabolic when used correctly — the growth hormone elevation and cortisol normalisation together create a hormonal environment that favours muscle preservation and repair over breakdown. The acute cortisol spike during the session is brief and followed by a below-baseline reduction; the GH elevation is the dominant and sustained signal. For people concerned about muscle loss during cutting phases, regular post-workout sauna is a useful strategy for preserving lean mass.
When should I sauna relative to training to maximise GH response?
Post-workout sauna produces the highest GH response — training already elevates GH, and sauna stacks a second stimulus on top of the training-induced peak. Sauna before training does not produce the same compounded effect and actually reduces training quality through fluid depletion and elevated heart rate. For the full timing analysis, see our article on sauna for muscle recovery.
Does cold plunge after sauna affect the hormonal response?
Cold plunge adds a distinct hormonal stimulus — primarily norepinephrine (up to 300% above baseline) and dopamine elevation. The GH response from sauna is largely complete before the cold plunge begins, so the cold phase adds its own hormonal benefits without cancelling the GH effect. Contrast therapy (alternating sauna and cold) produces a combined hormonal environment: GH from heat, norepinephrine and dopamine from cold, and cortisol normalisation from the overall parasympathetic activation of the sequence.
Does sauna affect cortisol levels?
Sauna initially raises cortisol during the session — it is a stressor, and cortisol is the stress response hormone. However, after exiting, cortisol drops below baseline as the parasympathetic nervous system activates during the cool-down period. With regular use (4+ sessions per week over several weeks), resting cortisol levels decrease as the body adapts to the thermal stress and no longer perceives it as threatening. This is the same hormetic adaptation pattern seen with regular exercise. The net effect of consistent sauna use is lower average cortisol, which supports testosterone production (cortisol and testosterone are antagonistic hormones).
Will sauna affect my testosterone if I use it after leg day?
Post-leg-day sauna amplifies the growth hormone (GH) response but does not meaningfully change the testosterone response beyond what the workout itself produced. Heavy compound leg exercises (squats, deadlifts) already produce the largest acute testosterone and GH spikes of any exercise type. Sauna adds an additional GH boost of 2–3x but the testosterone effect is neutral to slightly positive. The one concern: if you are training for hypertrophy and your legs are severely fatigued, the additional heat stress may extend recovery time. Ensure adequate protein and hydration post-session.
How does sauna affect female hormones differently than male hormones?
Women experience the same growth hormone increase (2–3x) and cortisol reduction pattern as men. The testosterone response is less relevant because women have 10–20x lower baseline testosterone. More significant for women: sauna reliably reduces menstrual cramp severity through vasodilation and endorphin release, may regulate irregular cycles through stress hormone reduction, and improves progesterone-related sleep disturbances in the luteal phase. The prolactin increase from sauna is proportionally larger in women, which has implications for breastfeeding mothers (potentially supporting milk production, though evidence is limited).
