things that will keep you from being able to go back to sleep

Dreaming about spiders all over your bed & bedroom--the kind that are just too large to vacuum up properly. (For some reason, one of them attached itself to a box of crayons, which was somehow small enough to fit down the vacuum cleaner's nozzle but too big for the opening into the bag, and...that's when I woke up, thank goodness.)

(Really, it was more of a very mellow nightmare, I suppose.)

Jack O'Neill would find this sort of bad dream almost relaxing, I suspect.
Tom Baker says he regrets not being in that now. The bad guy in The Five Doctors was Rassillon. But it also had The Daleks, The Cybermen and surprisingly it had The Master (loved Anthony Ainsley!) as a Good Guy! :)
Oh, I'd forgotten that it had the Master in it! Ainsley's take on the character did have a lovely bit of class to go with his eeeeevil. :D