For parents using mobile devices, a black screen uses less battery and prevents "screen burn-in" during long playback sessions. Safe Usage Tips
The black screen eliminates blue light exposure, which prevents the suppression of melatonin, the hormone essential for deep sleep.
The audio—often white noise or rhythmic "piş piş" (shushing) sounds—mimics the low-frequency vibrations and steady rhythms babies heard in the womb.