I’m a bit to the party and just listened to the podcast - I heard Jonathan mention something that’s really a common misconception. On advising a listener on how to relax after an evening workout he mentioned a cold shower as a way of lowering core temperature.
That’s not correct - even though it’s counter intuitive, a warm shower or a batch will decrease core temp, cold shower or even worse an ice bath cools you down for a short while but natural body reflex is to aim for homeostasis, which in effect raises core temperature.
That’s why we feel sleepy after a hot bath and a cold shower has quite an opposite effect.