Sleep is still very much a mystery that we have more to learn about, and it can be a strange topic. Why is it that some people only need four hours of sleep when I feel like I need ten? Does insomnia really affect my weight? So light affects how I feel when I wake...? Some things about sleep are more complicated than others, but one thing that we've known for a long time is that soothing noises can effectively put us to sleep.
For children, it might be that one bedtime song that always makes them sleepy, and for adults, it may be the recording of rain, but why these noises make us fall asleep is quite simple. When we hear comforting sounds like these, we train ourselves to relax. With this comes a recognition from past experiences that we are in a safe place and that it is ok to sleep. A large part of this concept is that of repeated conditioning, and this is why children will come to like one relaxing lullaby so much. We essentially decide that we've liked the outcome of dozing off in the past and feel safe to do it again.
Aside from this, having this noise when falling asleep will give us something to distract us from the other stimuli that keep us awake. It prevents us from focusing on our thoughts and clears our heads so that our consciousness can be allowed to fade. It also can muffle out external noises. The key to this is that it gives us a predictable tempo to listen to, instead of the erratic sounds that divert our attention. I know I often find myself falling asleep only for my mind to go off on a tangent at the sound of the downstairs fridge. Falling asleep can be a difficult thing because unlike our tasks during the day, you can't just focus strongly on the task at hand to complete it. Sleeping requires us to do the opposite and relax. Due to this, we find that the best way to achieve this mental state is to deprive ourselves of distractions. So, having some sort of white noise can do a great job of achieving this for us. Just remember that if you are going to play some sort of distracting tunes while you sleep that you don't wear earbuds and that you avoid prolonged screen time before bed!
