Say hello to Michel Siffre, the French explorer who thought clocks were overrated and caves were the ultimate Airbnb. Not once, but twice, he ditched daylight for a subterranean life—first for two months in 1962, then for a mind-boggling six months in 1972. Why? To see what happens when your body clock gets a timeout. Spoiler: he caught a 48-hour sleep-wake cycle, forgot what day it was, and discovered isolation is less “zen retreat” and more “please send help.” Who needs sunlight when you’ve got lethargy and bitterness, right?
