Many families do not need a perfect no-screen policy. They need a better final ten minutes. Fast cuts, bright visuals, and emotionally charged content leave children carrying extra momentum into bed.
The simplest improvement is a bridge ritual. If a screen happens earlier in the evening, follow it with something deliberately slower: bath time, a short tidy-up, one lap around the room choosing tomorrow's book, then reading and music.
Children rarely shift from high stimulation to deep rest without help. Stories and lullabies are useful because they give the nervous system time to descend instead of stop abruptly.