People do things for idiosyncratic reasons. If you enjoy what you are doing, I wouldn't necessarily change it but I'd take a look at it and understand where it is coming from and why you are doing it and what you are receiving from it? To me, riding a roller coaster to get my thrills is better than bungee jumping from bridges or climbing mountains? Similar sensation, costs less, takes less time, etc. If you have a problem with the dark movies though, if they're not wholly enjoyable but cause problems (nightmares, etc.) for you, then I'd see why you are doing them and see if you can find some other way to get the enjoyment without the pain.