Battery constantly drains overnight. Tracked it down to CTSY fuse circuit.

I'm wondering if in you experience you could point me in what might more likely be the cause of this drain. Door-locks, passive-restraint-solenoids? The fuse says it is used for Interior, underhood, courtesy, I/P, Trunk lamps, door locks horn relay, passive restraint system, deck lid release, power antenna, remote keyless entry, vanity mirror.

Mirror is not lighted. Does not have power antenna, don't know if it ever did. Driver side seatbelt is very slow to retract. Driver's door has a loose/broken outside handle. Horn works fine with fuse in place. All lights listed work and go out as expected. I'm leaning toward the seatbelt system or doorlocks but would love to hear your take.