The tourist zone in Playa del Carmen jostles with tourists of all ages right up until the shops and then restaurants close. After that things start to thin out quickly, after 1:00ish things simmer down considerably and only a few late night after hour clubs and cafes remain open. Even then police are present as well as local workers on late shifts and hotel security. With that being said, Playa del Carmen is typically very safe. We have not heard of any problems with tourists having issues with this.