Wait
You're tired, and so is Charmander, so you decide to wait until morning. Plus those grunts might be crawling around for you out there. One more question: Do you want Charmander to rest in your room with you, or in it's Pokeball in the rejuvenation area? In the rejuvenation area, it'll be healed more thoroughly, but if it sleeps with you, it'd be nice bonding time.
Your Options
Sleep with you
Sleep in the Rejuvenation area