I sleep very well, on the whole. When anxious, or dreading the next day, I can usually do as Winston Churchill recommended: "Turn out the light, say 'bugger everyone,' and go to sleep". But sometimes I suffer from Overactive Brain Syndrome, which happens when I cannot keep pleasant thoughts from going round and round in my mind.
In the days when I used to Do It Myself, I would start happily planning something I was making and thrash about sleepless for ages: "I know! I could make a frame of four by two, cover it with chipboard, and..."
Another time, looking forward to going to dinner with some agreeable people, I might think: "I wonder if Ginette is going to give us one of her sensational ragouts de gibier", but in a case like this I would soon drift off in gluttonous anticipation.
Nowadays I sometimes draft posts for OMF in my head when I wake during the night. If I think it is going to be a good one I get deeply absorbed and spend what seems to be hours drafting and re-drafting it. I am never wide awake or energetic enough to write it down, so as with dreams much of it is gone in the morning and the sleepless hours were mostly wasted.
On the other hand, if after a bit I realise that the post is not going to be at all interesting to anyone, sheer boredom will soon send me back to sleep. This happened last night when I was drafting this post. I did remember much of it, so I am publishing it; sadly, it might have contained some good bits that I have forgotten.