The problem I see with this kind of studies is that they don't measure long-term effects, and oh boy - do they exist. Its the topic I can be used as a bad example. When I was around 16, I found that my ideal sleep schedule was doing 20h awake and 6h sleeping. In those 20h, I'd spend around 13h in front of a monitor (monochrome, so less eye strain), and the rest doing the usual stuff (reading, eating, etc). I kept it for as long as I could (around 3 months), until it stared interfering with "life schedules" such as school. So instead of returning to the usual 8h sleep, I started sleeping when I could. It lasted a couple of years, until the brain couldn't take it anymore. After that, I spent the biggest part of 6 months sleeping (would be awake around 4-6h a day) and medicated (as far as I recall, no explicit sedatives). Fast forward a couple of years, and I'd do "marathons" like 20-40h awake, but then with 10-12h sleep time. Periodically, I'd need to sleep "a day" (usually around 14-16h) to feel recovered. In the past 6 or so years, my sleep schedules have been pretty normal, but I sill need to sometimes sleep "a day" (at weekends), and its very difficult for me to sleep only 8h a night. When I'm on vacations, I usually sleep around 12h as often as I can. Messing with sleep schedules (granted, in an extreme way) has had a profound negative impact in my life, and past 20 years, I still suffer consequences from my youth mistakes. The benefits I reaped from having "extra time" are dim compared to the long-term consequences not only on my health, but also on my personal life.