Nightshift wagie here. I often hear how night shifts are supposedly a slow killer due to them disrupting our 'natural' circadian rhythm. Yet I fail to find any concrete research or evidence where the negative effects are linked directly to the flipped sleeping schedule rather than things like sleep deprivation, weight gain, poor social life etc. To my understanding, circadian rhythms are governed by light, increasing drowsiness in poor light and increasing alertness in bright conditions. So, why do they even matter to a modern man who spends 90% of his life under artificial lights and can control the level of illumination however he damn pleases?