Sleep seeds are built for the eight-hour timer, not for a five-minute listen. They favour low frequencies, slow movement, and a texture that does not change enough to wake you.
Brown noise through a low lowpass filter is the base of most seeds here: it removes the hiss that keeps light sleepers alert and leaves a dense, even rumble. Lullaby seeds add a celesta pattern in the upper register, voiced like a music box with a soft attack.
The delta sub-pad seeds go lower still. A very low cutoff means the track is felt more than heard, which is useful if you share a room and need to keep the volume down.
Set the timer before you lie down. The last ten seconds fade out rather than cutting, so the ending does not jolt you awake.