I tried Everyman-3 last summer. It was a very weird experience. Highly unusual.
After a few times of failing to wake up on time, I became a bit alarm-paranoid. I once woke up on my own early, and jumped out of bed thinking two hours had passed (instead of 30 minutes). Turned out only 8 minutes had passed since I looked at my watch before going to sleep.
This reflects one of the cooler aspects of polyphasic sleep - you learn to fall asleep regularly in under 3 minutes. I slept on a bed, on a floor, on a lawn. You just learn how to relax and drift off immediately.
Also, once you've slept for 30 minutes, you don't want to sleep anymore. Your consciousness just regains control of your body and poof - you're awake.
It's not something I would do for years on end, because it can be difficult to accommodate having work and a social life, but it's very fun to do for a few months at a time. You gain a lot of time.
Eh, maybe. I haven't studied polyphasic sleep and I'm not a scientist, so understand that my opinion comes from someone who has slept monophasically, experienced quite a bit of sleep deprivation, and also slept polyphasically.
That said... what I was talking about is not at all like sleep deprivation. Sleep deprivation causes tiredness, lethargy, lack of energy. You wake up feeling tired and maybe your eyes or your head hurts. What I experienced with everyman-3 was nothing like that. It wasn't you falling asleep because you were unusually tired; it was you falling asleep because you willed yourself and your entire body to relax and let go of consciousness, almost like a sort of meditation. You wake up feeling absolutely refreshed and ready to go. In any case, it feels completely different from going to sleep tired or waking up sleep deprived; I don't know about the specific mental mechanism, as I am not a neuroscientist, as cool as I think it would be to be one.
Anyway, I would recommend giving polyphasic sleep a few tries. I only managed it after trying and failing twice (once because I kept oversleeping, once because social things got in the way). Also, I would not recommend doing polyphasic sleep for many months on end. At least, I wouldn't feel comfortable doing it, as who knows why it's possible. Maybe I'm depriving my body of very necessary sleep and preventing long-term learning or something - until it's more well researched, I wouldn't want to sleep polyphasically for more than a month or two.
In the morning I usually end up quickly turning my first round of alarms off and then crawling right back in under those warm and secure covers.
On a somewhat related note, I am going to start Uberman this summer. Does anyone have any experience with that?