If the litter box is messy, he will meow outside the bathroom door.
Feeding time? No worries. Homer will remind you.
But the other night, the meowing was pitiful. What could be wrong? I went through the usual routines, but nothing satisfied him. I finally went into the room he'd came from, turned on the light, and searched for anything that might be bugging him. Like a bug or critter. Nothing.
I left the light on and left the room. Silence. That was it. He just wanted the light on.