[driverdan]

I did a month of polyphasic sleep about 15 years ago. It's doable and was an interesting experiment but is not sustainable.

Mentally I felt 80-90%. I couldn't concentrate or think as well. I felt cold all the time as if my hormones were out of wack.

Towards the end of the month I was very sleep deprived. I would fall asleep and go into REM almost instantly. I slept through alarms, something I otherwise never do. A few times I shut the alarm off and went back to sleep with no memory of doing so.

An interesting side effect was that after going back to a normal schedule I needed less sleep. For months afterwards I only slept 7-7.5h a night instead of 8h.