If you have ADHD, your experience of bedtime is probably familiar: your body is exhausted, your brain is not. Lying in silence doesn't help — it gives your mind a blank canvas to fill with every unfinished thought, half-remembered task, and random tangent from the day. Silence is the worst thing for an ADHD brain at bedtime.
A bedtime story solves this by occupying the exact channel that would otherwise run wild. Your verbal-narrative attention — the part of your brain that follows stories, processes language, and builds mental images — gets something to do. And because that channel is occupied, the restless, topic-hopping, "what about this, and this, and this" loop has nowhere to go. The story doesn't need to be gripping; it just needs to be present.
Our stories are a good fit for ADHD listeners because they're low-consequence. If your attention drifts for a few minutes (it will), you haven't missed anything critical. The narrative is always in a gentle, self-contained moment when you drift back. Layering ambient sounds adds a second input channel — your brain processes the story and the rain simultaneously, which can be exactly the level of stimulation an ADHD mind needs to feel settled enough to sleep.