What is pink noise? Pink Noise is an incredibly relaxing and healing sound. Technically speaking, this is a signal that has octaves of the same energy. The color of the noise is determined by the energy of the sound signal. 

Specifically, it depends on how the energy is distributed over various frequencies or on the speed of sound.

Pink noise is made up of all the frequencies we can hear, but the energy is not distributed equally between them. 
It is more intense at lower frequencies, creating a deep sound. Since your brain continues to process sounds while you sleep, different noises can affect your rest.