Sleep
Slow ribbons of light drifting across a night sky
Falling asleep to sound only works if you're not lying awake worrying about turning it off later. That's the whole idea here: set a duration, and both the soundscape and the visual scene ease themselves out gradually, ending in quiet and darkness rather than an abrupt cut that can jolt you back awake right when you're closest to drifting off.
No clock-watching
Set it and forget it, twenty minutes or more, then let yourself actually drift instead of lying there wondering when to turn it off.
Nothing to jolt you awake
Sound and picture dim together, slowly, so the last thing you notice is everything easing off, not a sudden cut to silence and black.
Something quiet to rest your eyes on
Eight slow, dark scenes built to be looked at with heavy eyelids, pick whichever one feels least like something to pay attention to.
One more thing that helps
Your screen's brightness matters more than people think. Turn it down as low as it'll go, or let your device's night mode handle it for you.
Low-frequency noise, brown noise especially, masks sudden environmental sounds like traffic, voices or doors that would otherwise trigger a brief arousal response. It works best when it's consistent and non-rhythmic, which is why it's such a common pairing here.