I wake up a lot - can't remember the last time I slept solidly. Usually about twice during the night, but sometimes very frequently, and sometimes I'm awake for quite a while, although usually sleep again quite quickly. A few years ago when I was depressed I would regularly be awake between 1am (3 hours after going to sleep) and 4am (2.5 hours before getting up). It didn't make me tired so I would do Sudoku or go on the computer and not bother to try and sleep. Nowadays I do spend many days feeling half asleep due to waking up so much, but being tired does not make me sleep more solidly. I am a morning person and sleep better in the first half of the night. After that, sleep is almost optional, and I am happy to get up early.
I wonder if I have some type of sleep disorder as I seem to spend most of my time asleep dreaming - sometimes wake up after only half an hour sleep and remember dreams, which shouldn't really happen apparently. If I am stressed by noise (which often happens), I frequently have very vivid, realistic dreams where I wake up in my bed and either go out to investigate the noise or shout at people to try and stop it. These can happen multiple times in sequence, so I am rewaking into new dreams of waking up in bed. Very confusing, and I end up not being completely sure whether some of it actually happened - sometimes I can identify things in the dream which are not true in reality (for example, once I went into the corridor outside my flat to complain of noise and there were disco lights flashing different colours), but other times I can't be sure whether I have done things or not. I also sometimes have lucid dreams, and frequently spend time in a state of semi sleep when I am actively thinking about things but have lost my reason, so everything starts going very bizarre. I also get random involuntary thoughts (which are people saying random sentences, so could be thought of as voices, except I don't actually hear them) frequently as I am trying to get to sleep - these may be hypnagogic hallucinations due to mild sensory deprivation. Once I heard voices and had semi sleep paralysis - my impression was that half my brain had gone to sleep and the other half was awake still, listening and thinking how bizarre and frightening it all was. Again random, but I actually heard them, in a horrible hollow voice. Fairly frequently I find I have too much physical energy and cannot stay still in bed, let alone sleep. Makes my legs ache because I have to move all the time. When this happens however I am usually in an excessively good mood, so I don't mind.