Yeah it's one of those things where there are no hard and fast rules, although broadly I think folk fall into one or other category.
I find I do have a strange tendency to have several nights of a good night's sleep, maybe too much, then I have a restless night. This morning/last night, was one of those restless nights. I am due a phone appointment, so needed to be up anyway, but I was still awake at 4am, with the alarm set for 7:30. At 4am, I got up, put a waiting load in the washer, made a slice of toast and a glass of milk, then managed a couple of hours sleep.