Just to add onto this with an anecdote, I experienced this phenomena for a smaller amount of sleep: 1-3 hours per night. But I had other physical effects such

Just to add onto this with an anecdote, I experienced this phenomena for a smaller amount of sleep: 1-3 hours per night. But I had other physical effects such as a persistent headache - it was obvious it was bad for me. It took a lot of effort to reset my body to obtain a more healthy amount of sleep. I think I went about a month with 1-3 hours per night. The initial cause was "sleep regression in twins", but that was only for 2 weeks. The next 2 weeks was how long it took me to get my body to sleep more than a couple hours per night.