For a few months when I was 18 or 19 I was utterly ... free. For lack of a better word. No job, no responsibilities. I slept and woke when and for how long I wanted. Was staying in a friend's basement that was pitch black 24/7.

I found that I naturally drifted towards something like 28 up, 12 down. It varied a lot, but was way longer than the normal 16/8 shtick we're stuck with. Also, I never felt more alert and alive before or since.