Awake at 3am. Here is something low and plain.

Why it works

The page is dark so it will not wake you further, and it has one main button so there is nothing to decide. The sound is the deepest on the site, brown noise below 180 Hz, and works best in headphones. It is generated as it plays and fades out after four minutes, so you never have to reach for the phone again.

Three in the morning makes small things look large. Nothing here will argue you out of that, since arguing is also being awake. But if the thoughts have begun, the middle button puts a calm voice over the noise, speaking of something that was settled two thousand years ago.

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.