"a shorter amount of sleep and a nap"
I heard that the Spanish habit of taking a siesta, a nap in the afternoon, results in greater productivity because sleep recharges the brain.
Anecdotally, I have observed, at theatre shows in London, that many more audience members fall asleep in a matinee than an evening show.
I think the Spaniards figured out a sleep pattern that better fits the natural human cicadean rhythm than everyone else, who favor one sleep session each night.
The problem is most jobs don't factor in any opportunity to nap for an hour after lunch.
On another note, I find I wake up when it gets light, no matter how much sleep I've had, so I sleep better in the winter than the summer.
Weel, that is a hard thing to do here as where I am in the wniter, the sun rises at about 10am and sets at about 3 and in the summer, sets around 1100 and rises at 3 am :P
The siesta life would work well for me and it is kind of what I try. After work, I try to grab 15-30 minutes.
Oh man, I'm glad I don't live in Finland. Or maybe, if I did, I'd just learn to black out every window in a room. :)