> being sleep deprived for months does not make you bipolar maybe, but depression can and does happen

It shaves off 10 to 20 IQ points in me when I'm on a bad streak. I have failed FAANG interviews because of bad sleep. I still probably would've failed them, but it'd have been much closer. I literally remember one coding interview where I was thinking "if I just had enough sleep, I'd have a solid shot" (the other coding interview was so easy I could even do it in my half-ragged sleep-deprived state).