The curse of being single, and getting into bad habits with late nights. When I wasn't I spent less time online at night, had more of a sensible bed time, and would get up the next morning earlier, whether or not I woke during the night. I definitely sleep better on the digital free days, when I do other things like reading, repairing things. The annoying thing is I would never consider training without a warmup, at the gym or dojo, but sleep without some winding down is almost always poor sleep.
This is incorrect. Sleep is all about getting into a regular pattern. Break that pattern and problems will start. Sleep is broken into two parts, physical and mental repair, so go to bed to late, or rise to early and one of those will suffer. You can't go to bed early today and expect to get to sleep straight away. This is the mistake many parents make. Read my thread on entrainment, it take 7-21 days to become entrained to a new sleep pattern.