Search for recent threads on sleep referencing "first sleep". Seems the electric light has made us forget most sane humans through most of history would sleep at sunset, then wake a few hours later in a relaxed blissful state, then sleep again. Methinks what you experience (not uncommon) is natural behavior, subverted by not realizing you're supposed to go back to sleep after about an hour of some nocturnal activity.
Yes, inasmuch as we "need" sleep at all. There are many species that dramatically shift their sleeping patterns over the course of the year--such as never sleeping during months-long migrations--and come out with no "sleep debt" accrued at all. This lends to a conclusion that the brain really just requests a certain amount of sleep, and is unhappy if it doesn't get it--but it can request less sleep in the first place with no physiological effect.
We could probably figure out a drug that would put us into a state where we don't need to sleep, ever--the resulting state just might not be something very much resembling "sentient human consciousness." It might not allow for memory-formation or System 2 analysis, for example, thus making you go through life only relying on the sort of "thinking" you do while dreaming. Animals that don't sleep, or that sleep very little (e.g. horses, at two hours per day) are also likely "stuck" in this state by design.
The real question is whether we could get anything productive done in this state, and that might be possible--it seems somewhat to resemble "flow."