The crash of ocean waves, the babbling of brooks, the pitter-patter of rain on shingles — many people swear by these watery sounds to help them fall asleep and stay in la-la land. Why does flowing “agua” apparently have such a powerful and popular drowsing effect?
Part of the answer lies in how our brains interpret the noises we hear — both while awake and in the dead of night — as either threats or non-threats.
Certain sounds, such as screams and loud alarm clocks, can hardly be ignored. Yet other sounds, like the wind in the trees and waves lapping ashore, we sort of tune out.