The sound of waves crashing, the gentle flow of a stream, the pitter-patter of rain – many people say that these water sounds help them fall asleep more easily. Why is this the case?
Part of the answer lies in how our brains interpret the noises we hear [both when awake and during the late night] as either threatening or not.
“These noises are non-threatening sounds, which is why they have a calming effect on humans“, said Associate Professor Orfeu Buxton, a health expert at Pennsylvania State University (USA). “They seem to be telling us: Don’t worry! Don’t worry!“.
Louder noises tend to make it harder for us to sleep. However, perhaps more important than the volume here is the nature of the sound (in other words, whether that sound activates the brain’s threat detection system and wakes us from sleep).
Non-threatening sounds help calm people.
“The type of noise will be a determining factor in whether you wake up or not, as the information about the noise is processed by our brains in different ways” – Mr. Buxton stated.
For example, while the sound of crashing waves may vary in volume, it is entirely different from a scream or a phone ringing suddenly penetrating the silence and immediately reaching a high volume.
“In the case of a scream, it is no longer considered ‘normal noise’; it transitions directly into a high-pitched sound” – Mr. Buxton noted.
According to a study by Professor Buxton at the hospital, even at a low volume of around 40 decibels – essentially a whisper – alarms from hospital equipment also woke study participants from sleep (whether it was light or deep sleep).
Biologically, we humans seem to be programmed to react to sudden noises because they may signal very bad news.
“We are mammals, but we are primates“, Mr. Buxton said, “primates will alert their kind about threats“. In the case of primitive humans living in small groups, “a scream could signal that someone in the tribe was being eaten“.
According to Mr. Buxton, another reason why the sound of water makes us sleep better is that: Non-threatening noises, when at a relatively high volume, can drown out sounds that trigger the brain’s threat detection system.
“It can help suppress other sounds that you cannot control, such as when someone is flushing a toilet in another part of the house, or when there are taxis and vehicles outside…” – Mr. Buxton explained.
All of this makes it understandable why sleep aids using flowing water sounds have become popular over the decades, across various media, from cassette tapes to MP3s, and today’s mobile applications.
However, based on his research results and other studies, Professor Buxton also warns against relying too much on mobile devices.
“Phones are unlikely to protect your privacy and peace“, Mr. Buxton said, “You might think you’ve turned off all notifications, every message alert and update, but if your phone isn’t completely off, you still run the risk of unintentional interruptions“.
Some people also report feeling the need to use the restroom when they hear running water. Professor Buxton noted that aside from that case, you should continue to enjoy the gentle sounds of water to drift deeper into sleep.
