Almost every day before I go to sleep. I seem to have some mental connection between sleep and death, because most other times it doesn't come to mind.
Unfortunately for me this has connected the act of going to bed with a negative emotion - fear. I've had many nights where I simply stay up too late attempting to fatigue myself to the point where I know I'll fall asleep quickly. The next day is not kind to me for it.
"How dreadful!" cried Lord Henry. "I can stand brute force, but brute reason is quite unbearable. There is something unfair about its use. It is hitting below the intellect." ~ Oscar Wilde - The picture of Dorian Gray