For reference, 21m, college student. Saw a YouTube videos about myths about sleep, got me thinking about questions I have about my own sleep patterns:

1. I normally sleep just fine, but every once in a while, I just can't sleep until past 2 am (I normally go to sleep relatively early, so that's very late for me). It seems pretty random, and I've never tracked it, but my guess is that it's maybe one night every other month. What's that about?
2. How do I figure out why I've been waking up in the middle of the night lately, like 4 am? Normally, I just go to the bathroom, and then go back to bed, but still, this is a relatively new phenomenon. Is it because I moved and am not adjusted to the new location (I moved in September)? How can I figure out the cause?
3. Why does masturbation make me want to fall asleep?
4. I remember as a kid, having my parents reading a story to me about a kid who eventually fell asleep on the train by listening to the wheels on the tracks. Do gentle repetitive noises like this actually help sleep, or is that just something an author made up, and now I've internalized?