What is sleep pressure?
I was reading an article on melatonin, and one of the commenters said something about 'sleep pressure'. I did a web search to see what it was, but web searches don't often seem to allow exact phrase matches anymore (so, I got results about other sleep topics and blood pressure instead).
The commenter said, among other things, "The other, the S process is influenced by sleep pressure."
The Wikipedia article on sleep mentions homeostatic sleep pressure (but it doesn't define it; nor does it mention another kind of sleep pressure).