If your at the graveyard its too late for you to need meds....
Seriously though:
Cons: You will probably have limited staff, and also less people to call in case of a problem, it is probably the most dangerous time for crazy drug seekers, and prolonged night shift work tends to make you gain weight because you snack and drink sugary stuff to stay awake. Usually when something goes wrong, it goes WRONG. Going anywhere on vacation sucks because you spend your whole time with your sleep schedule backwards, unless you go somewhere open all night like Vegas. You sleep most of the time things are open, so getting anything done at a place open 9-5 can be a pain.
Pros: limited staff, so you can have some quiet time, no store managers breathing over you, very few people asking what asle the soap is in, you may have some down time, so you can bring some knitting or a book or something. Shift differental, and you can probably work as much as you want because less people want that shift. May only have to work three days, or have 7 on-7off option. Good for people with kids because they can go to work while their kids and spouse are asleep.
If I could play on the internet in my down time I would jump all over night shift at least for a few years. But if I just had to sit there when it was slow, I think I would bore myself to death in a few weeks. For long term though, I think it ages you, so I wouldnt want it.