Metronomes are devices (now commonly in the form of an iPhone app) that help keep steady time when practicing music. A song generally needs to keep a steady tempo (think speed), otherwise it will sound rushed, dragged, or otherwise chaotic.

The most common time signature is 4/4, which means that you're hearing a quarter-note pulse every time the metronome makes a sound.

There are a few different reasons listening to a metronome can help with sleep: It gives you something to focus on. Do you find that your mind won't stop racing when you hit the pillow? Focusing on a metronome sound can help to calm your mind.

A metronome is a device that produces a steady beat or pulse to help musicians play in time. It is measured by beats per minute (BPM). A tempo marked as 60 BPM equals one beat per second, while 120 BPM equals two beats per second, so on and so forth.