Why do so many people with autism have sleep problems?

 Why do so many people with autism have sleep problems?

My brain just won’t shut off. I'm not a doctor, so I can't tell you why. I can only tell you what it feels like to me and my experiences dealing with it.

When I was in my teens and 20s, I would lay awake thinking about the humiliations I'd suffered during the day. I took teasing very personally. I did not understand that teasing is done as a test, and to pass it you have to laugh it off and give a bit of it back. Or I'd have an awkward social encounter. I would lay there thinking about whatever had happened, trying to figure out what I should have said. I did a LOT of negative self-talk.

If I just laid down and tried to sleep, I'd lay there in the dark literally for hours. Often, I'd fall asleep while still conscious and have terrible nightmares. It took me quite a long time to figure out some coping mechanisms. The main one was to read until I reached a specific point of exhaustion. If I stopped and turned off the lights too early, I'd lay there awake. If I wanted too long, I'd get a second wind and be awake for hours longer. The worst thing was to discover that I had run out of books. Or if my wife said even one word to me, my mind would start racing around again and I'd be fully awake in seconds.

I had a teacher notice how tired I always looked and asked me a lot of questions. Unfortunately, my parents are much more worried about giving the appearance of a normal family. They denied that I had any kind of sleep problems or depression issues and made sure no more help was forthcoming.
I bought a Walkman knockoff, and I'd fall asleep to music. When I got a new album, I'd fall asleep by the 2nd song, then I'd be awake 'til the third, etc... until I was awake for the entire album. So that'd only help for a week or so. Cable TV helped... I could watch science and nature shows. Now with the internet, I can set up a short music playlist or set a science or nature show playing.

It has to be something that occupies my attention but doesn't require me to really follow closely. My wife is incredibly tolerant of this. It is not uncommon for me to wake up hours before I need to get up. In my 20s, this meant hours of me looking at the clock and calculating just how much time I had left to sleep. Now I put on a science or nature show, or some music. It must be so quiet that I can barely understand what they are saying.