I am bipolar so I am naturally predisposed to needing less sleep during manic episodes. When I was 20 and unaware of my diagnosis but probably in a manic episode, I successfully maintained the Uberman sleep schedule for three months. Even for someone like me who can function well on minimal sleep, it was definitely challenging, but it's absolutely doable and does come with some real benefits, mostly productive hours. The biggest hurdle wasn't the physical demands it was the social impact. Having to tell guests that you need a 30 minute nap in the middle of hanging out is incredibly awkward. The schedule also becomes quite rigid because skipping even one nap really throws everything off. For me it was manageable but the lifestyle restrictions ultimately made it unsustainable.

There was a nice and friendly Usenet group. It's no longer active but archived here[1]. It has loads of information and journals of people that tried it at the time. Most of us also dappled with binaural beats (alpha, theta and delta waves) during the naps. They helped with falling asleep and waking up.

[1] https://groups.google.com/g/polyphasic