Deep noise for the second half of the night.

Why it works

Waking in the middle of the night is ordinary. Staying awake is usually the fault of whatever you started thinking about. This is the lowest and plainest sound here, brown noise below 180 Hz, and it suits headphones in a dark room. It asks for nothing, and it does not loop.

If the thinking has already begun, a low hum will not interrupt it. A voice can. This one is not telling you to relax or to breathe. It is telling you, slowly, about a boy who liked tide pools. The page fades itself out after four minutes either way, so there is nothing to switch off.

What you are hearing

• Deep brown noise. The same brown noise low-passed at 180 Hz. Almost everything above a cello's lowest string is gone. It needs headphones or a real speaker.
• The voice. The first four minutes of Aristotle, the Greatest Philosopher, a Lullable story, in a synthesised voice. It only plays if you bring it in.
• The ending. The preview lasts four minutes. Its last ten seconds are a straight fade to silence, so it never stops abruptly.

For a real recording that runs forty minutes, the Lullable iPhone app has rain, waves, a campfire and plain noise, with no voice and no music.