How does heat affect growth hormone?

Heat exposure, particularly through sauna use, significantly affects growth hormone levels. A study discussed by Andrew Huberman showed that subjects experiencing two hours of sauna exposure at 80 degrees Celsius had a 16-fold increase in growth hormone levels on the first day. However, this effect decreased with more frequent exposure; by the third day, the increase was only about three to four-fold. This suggests that while heat acts as a stressor that can spike growth hormone levels initially, the body adapts to regular heat exposure, diminishing the hormonal response over time 1 2.