As far as I understand, energy is conserved. Light inside a closed box will ultimately turn to heat too.

I just have a motion sensor in a hallway his zoom pattern follows. It’s not between the bedroom and the bathroom, so it would only trigger with the cat or a burglar (the automation is inactive during the day).

I’ve got a few fun ones:

At night, my cat sometimes gets the zoomies, so I have a projector pointed at a wall with a motion sensor. When he goes on his tear through the house while we’re sleeping, the projector turns on and plays a video of strings moving on the wall. This tires him out without him screaming at us to play with him. It turns off again after a few minutes with no motion.

The lights and Roku screens in my office are on a motion sensor, but are also linked with a seat sensor so they don’t turn off when I’m at my desk. Sitting at the desk also sends a Wake on LAN packet to my computer. Sitting at my electronics workbench changes the lights to bright white with another seat sensor.

Lights (HA), desktop wallpaper (with Wallpaper Engine), and in-computer RGB (using OpenRGB) change from blue/pink during the day to dark red/orange at sunset so being in my office late doesn’t mess with my sleep.

A macro button next to my keyboard disables my screens and turns on a fan pointed at my VR area for workouts.