Do ghosts only come out at night or something?

Not saying I'm a believer, but I'm not a disbeliever - just confused. I've been watching a lot of "ghost hunting" shows lately and all of the investigators only search at night AND with the lights off. Is there any belief that ghosts are more comfortable in the dark or something? i dont understand why nobody investigates in the daytime and collects evidence then. You can only see a ghost at night or feel it in the dark apparently..