Binaural beats for sleep.

Binaural beats are a headphones thing — the reason is the mechanism. Each ear gets its own steady tone, a few beats apart, and your brain hears the difference between them as one slow pulse. The tones themselves are steady; the pulse they make is slow. No sound like it exists in the room; the beat only exists where your two ears meet.

If you've met theta before, it's the band your brain sits in as it falls asleep — slower than the busy waves of the day, faster than deep sleep. Riding a beat down through it feels less like being pushed somewhere and more like being walked to a door.

That pulse is the useful part. Your brain has a habit of following a rhythm, and a beat that slows down is a beat your brain slows down with. Deep descent starts in theta and eases down into delta, the slow, deep rhythm of sleep itself. By the time the beat reaches the bottom, you're usually gone.

Put headphones on rather than a speaker; the effect needs both ears. Then press play above, close your eyes, and let the beat carry you down. Most people never hear the end of it.