Noise can interrupt sleep, and interrupted sleep is less restorative. Undesirable noise, like traffic that doesn’t disturb sleep can still affect sleep by changing the time we spend in different sleep stages, increasing lighter stages and decreasing more restorative slow wave and REM sleep. Noises during sleep may increase secretion of hormones like adrenaline and cortisol and elevate heart rate and blood pressure.

Short-term, fatigue, irritability, and poorer mental health are associated with exposure to nighttime noise. Long-term, poor quality sleep due to noise can have a number of adverse effects – heart disease and stroke, high blood pressure, weight gain, increased use of sleep medications , decreased overall health, and certain types of cancer.

A very popular solution is to mask unwanted noise with a more desirable acoustic environment. Many find that masking background noise helps to distract from anxious or intrusive thoughts and readies the mind for sleep. The sounds found to be universally most effective are: