The Sound of Sleep says "white noise" is not the only noise with color out there, and they can all affect our bodies in different ways. There is pink noise (white noise with a slightly lower pitch) which sounds like soft rainfall or whistling wind. There is also brown noise, which sounds like the rumble of ocean waves or the howling of stronger winds. The three don't work the same way — white noise may be beneficial for people with memory and concentration problems and tinnitus, pink noise may help memory retention, and brown noise is associated with relaxation, better focus, and better sleep. Michael Grandner, director of the Sleep and Health Research Program at the University of Arizona, describes pink noise as a "hiss," and brown noise as a "shush" — and white noise falls somewhere in between the two (via Time).

But Time notes that research shows no one noise is better than the other when it comes to helping someone catch those needed zzz's, which is one reason why just any old white noise machine might not work for everyone. Also, the use of white noise machines is somewhat controversial, according to Grandner. He says, "Biologically, you don't need this to sleep, and if you use it every night, you can get so used to it that you can't sleep without it."  Basically, he believes a white noise machine is just a crutch that helps support a pretty harmless dependency, because as he puts it, there is no research out there that supports the absolute need for white noise machines.

But at the end of the day, it's really all about what helps you get a good night of sleep, and if your white noise machine or app (which may come bundled with brown and pink noise options) gets you there, go for it. It may just take some time to find the perfect noise that helps you drop off to a peaceful slumber.