Up too late studying? Want nothing more than to get a little bit of sleep? Sounds like you're exhausted — all of your energy has been used up. Exhausted is spent, drained, and depleted.
Though you might associate the word exhausted with people, it's a word that can be used to talk about anything that's depleted. You might want to continue traveling around Europe, but if your funds are exhausted, it's time to go home. If you're trying to get in touch with the airline so you can make a reservation for your homeward-bound trip, your patience may become exhausted after being placed on hold for hours.
adj depleted of energy, force, or strength