According to the National Sleep Foundation, while you sleep, your brain continues to register and process sounds on a basic level. Noise can jostle your slumber—causing you to wake, move, shift between stages of sleep, or experience a change in heart rate and blood pressure—so briefly that you don't even remember it the next morning. Whether sounds disturb your sleep depends on factors such as the stage of sleep you're in, the time of night, and how loud or startling the sounds might be. Noises are more likely to wake you from a light sleep (stages 1 and 2), than from a deep sleep (stages 3 and 4), and tend to be more disruptive in the second half of the night.
Many slumberers find that utilizing something like a white noise machine can reduce the difference between background sounds and a "peak" sound, like a door slamming, giving them a better chance to sleep through the sound undisturbed. In addition, white noise can help someone that has difficulty falling asleep or staying asleep, creating a constant ambient sound that could help mask activity from inside and outside the house.
In the bedroom, white noise can be created by a sound conditioner, a fan or an air purifier, or anything that is a consistent and soothing backdrop throughout the night. The BEDDI alarm clock app includes several white noise options with a sleep timer including a fan, rain, ocean, forest, and wind. And the new BEDDI 2 includes these same white noise sounds without using the app.
White sounds contain a lot of different tones but each tone has the same intensity. It's monotonous, predictable, and boring. And predictable sounds help drown out loud noises so you're less likely to hear them. Plus, the monotony of white noise makes it easy to ignore. However, before you rely on white noise, you might want to experiment with the volume and type to find the white noise that works best for you, or if you have a sleeping partner, the sound that works for both of you.