I've done the polyphasic uberman schedule for 2 months (years ago). The first month is hell adjusting to it until your body is so starved of REM you don't give it a choice.
The 2nd month went well enough if you keep to the schedule SUPER STRICTLY. 20 mins late for a nap and you're screwed up for days getting things back on track. I ended up getting a cold and put it on pause, but never picked it back up again fully.
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