People will misinterpret you, but if something is bad for you at any age, then the parent should be taking their own advice. "If you can't do it with self-control, then don't do it, or find a way to make it work..." applies to everyone, regardless of roles. No, you don't have to wear pajamas and sleep the same times they do, but you cant tell them how healthy it is to get a full night's sleep with the screen down if you're (frivously) harming your own sleep.