Steam or sauna

Sauna or steam: Either can work—there is no special advantage to dry versus steam sauna in the discussion; the key is raising body temperature safely. Heat exposure is associated with lower cardiovascular and all-cause mortality risk, and it raises heart rate, blood flow, and blood volume. It can resemble cardiovascular exercise, but does not provide exercise’s loading and other benefits, so it is not a replacement for exercise. 1 2 3

• Repeated heat exposure: A study protocol involving repeated sauna sessions found reduced cortisol; heat exposure can also raise growth hormone. 4 5
• Intense growth-hormone protocol: A study used four 30-minute sauna sessions in a day, with cooling breaks, and observed a large growth-hormone increase. Huberman described this as an extreme protocol and advised doing such intensive exposure no more than about once weekly if pursuing that effect. High heat carries overheating risks, so use caution. 6 7 8
• Hydration and spacing: Hydrate, avoid overheating, and allow cooling breaks between sauna sessions; repeated heat exposure should be spaced appropriately, especially for the intensive growth-hormone protocol. 9 10
• Alternatives: A hot bath or another sufficiently warm environment can provide heat exposure if a sauna is unavailable. 11 12
• Sperm effects: Excessive testicular heat can reduce sperm production and motility; the discussion notes these effects were reported with sauna or hot-bath exposure. 13