I prefer noisy, busy music to fall asleep to, albeit at low volume.
My brain feels like it needs to attend to the unassuming events in quiet music, just as one would want to turn off a leaky tap in the bathroom.
The thrashing over-stimulation of hardcore or metal is like having to sleep during a thunderstorm: there's too much for a drowsy consciousness to confront and so, quite sensibly, it capitulates.