Ha, my chicks did the same thing! They were so loud that I started turning out the lights at 9PM. I go to bed at 10PM, so this meant that I spent an hour watching television in the dark (with the sound turned up, so I could hear it over the cheeping). By 10PM they would have quieted down enough that I could get some sleep.
Two things changed:
1. They gradually got used to the darkness, and every night they freaked out less and less.
2. I moved to a gradual shut-down. I would turn off one light, wait 5 minutes, turn off the next light, etc. It frightened them less when the lighting levels dropped gradually. As opposed to suddenly being plunged into darkness.