What changes the behavior answer
Give the bird a predictable bedtime, quiet room, clean air, and darkness. The goal is real rest, not just a cover thrown over a busy cage.
Look at the household schedule
Television, late lights, guests, barking, kitchen noise, and people walking past the cage can keep a bird half-awake.
Use covers carefully
A cover may help some birds, but it must allow air, avoid overheating, and never be used as punishment for noise.
Watch daytime behavior
A tired bird may nap heavily, scream more, bite faster, act frantic, or become hormonal. Health issues can look similar, so watch the whole bird.
Simple target
Protect a steady, quiet night before blaming the bird's personality.