did you know that a man lived in a cave without sunlight and any sense of time but why would anyone do something like that well in 1962 Michelle cifra conducted an experiment to study human circadian rhythms and time perception he lived deep underground in a French Alps cave removing all external time cues like sunlight and clocks for two months he lived like that as time passed cif's perception of time shifted dramatically and soon he lost all sense of time passing with erratic sleep patterns blurring wakefulness and sleep despite the irregular schedule his body functioned surprisingly well his body temperature hormone levels and cognitive functions remained stable showcasing the resilience of the human body's internal clock thank you for watching