There is a water dripping noise in the bathroom wall or ceiling that stops when I turn on the bathroom sink faucet. Then maybe 6-10 hours later it begins again. I don't have the heat or a/c on during these times. During the night/morning 11 pm through 6 am it happens a couple of times. This is a condo in Florida. About 15 years old. Thanks. Driving me crazy.

Is your ac in the attic?

Possibly expansion of the piping, particularly with hot water. Try this-run cold, listen and then run hot water. What do you hear?