I used to habitually play bullet and blitz chess online, which confirmed the necessity of sleep for me. After a 6 hour night of sleep I noticed my rating would drop significantly the next day, and after several low sleep nights in a row it would take days to recover completely. A graph of my bullet rating over time clearly showed the periods of low sleep.
Most people don't have a measurement that objective. After I stopped playing chess so much in college, I even caught myself trying to excuse my poor sleep habits by telling myself I wasn't falling asleep in lectures and I could still finish my homework.
Most people don't have a measurement that objective. After I stopped playing chess so much in college, I even caught myself trying to excuse my poor sleep habits by telling myself I wasn't falling asleep in lectures and I could still finish my homework.