About a year ago, I saw a Hacker News comment by someone claiming to sleep on average 0-2 hours a day. There were 20 replies to that comment but (he) never responded to any questions, and continued posting replies to other threads in the coming days. I pulled all of (his) comments and their post times via the Hacker News API and plotted it, which revealed an interesting lack of posts from midnight-6AM EST across ~150…
We know there have been some who really needed much less sleep but they are widely known to be geniuses or hyper-productive (Nikola Tesla, Elon Musk etc.)
Most people who claim to sleep only 2 hours a day or whatever are probably being a little dishonest or are miscounting.