Sounds during sleep— helpful, or harmful??
There has been an explosive surge in the number of YouTube videos and dedicated mobile apps geared towards helping people with sleep and sleep optimization— but the types of sounds you listen to can impact not only sleep quality, but also potentially your memory!!
A very interesting article published in the journal iScience analyzed the effects of random auditory stimuli during sleep (for their experiment the researchers used random “clicks”) upon neural activity and memory consolidation. What they found should inform our approach to sleep sounds— the random clicks during sleep were found to reduce slow wave sleep, diminish sleep depth, and impair memory consolidation!!
Sleep is known to facilitate the consolidation of our memories, through a dynamic interaction between the hippocampus and the neocortex of the brain, using slow waves (mechanism reviewed in a good article found here). The researchers found that the random sounds disrupted this process by interfering with the slow waves and resulting in memory deficits!
Yet the story here is more nuanced! The Sleep Foundation, which is informed and directed by numerous sleep specialists, recognizes that most of us are subject to noise at night— certainly worse in the urban setting, particularly from loud vehicles, motorcycles, emergency vehicles, etc. They suggest that some background sounds may drown out unwanted noise, but admit the research proving this benefit is conflicting and advise that use of background sounds should be a personal preference. They also explore the various categories of background sound, including white noise (static), pink noise (light rain), and brown noise (waterfall).
Many of my patients in clinic advocate using apps like Calm and Headspace, or ASMR videos to help them relax and sleep. More research needs to be conducted to discover the optimal use of sounds during sleep, to ensure excellent rest, and avoid disruption to the various phases of sleep, as well as any negative impacts on our long term memory. But very importantly, as I emphasize in my book Optimized, you must engage in sleep hygiene to achieve the best possible sleep!
