Hearing And Sleep: How Noise Affects Our Sleep
Updated: Aug 1, 2018
It is perhaps one of the senses we blame the most for a poor night's slumber. Sounds which we barely notice during the day can cause significant disruption to our sleep, especially when they are sporadic. The good news is sound perception is the most studied area in how the senses affect our sleep.
Ever known someone who can sleep whilst a party is going on around them? Or someone like me who stirs at the slightest sound of a squirrel farting outside the window? This difference was explored by Jeffrey Ellenbogen and his colleagues at Harvard.
In this sleep study, twelve participants were hooked up via electrodes to an EEG/fMRI which measured their brain activity whilst they slept in a pitch-black, soundproof room. The experiment was repeated, this time playing 14 sounds such as a toilet flushing and street traffic, at 30-second intervals. The volume was increased each time until the volunteers’ brainwaves showed signs of arousal.
They discovered the pattern of brain activation associated with auditory stimulation was identical in both wakefulness and sleep. What did differ was that certain regional activity was reduced during sleep, compared to wakefulness. Simply put, the sleeping brain is able to detect and categorise certain aspects of stimulus significance, such as your own name being called, whilst ignoring the rest. The brain’s sensory relay centre is the thalamus and it's here that our sensitivity to sound (or lack of) may be located. Sleepers who tolerated louder sounds before waking showed more numerous short bursts of activity on specific wavelength during non-REM sleep, than those who woke more easily. This contributed to the theory that the activity of the thalamus may be to dampen sensory input in order to stop the brain perceiving and responding to it. Since I'm a light sleeper, I can only conclude my thalamus is to blame for my inability to ignore any bumps in the night. Thanks thalamus.....
A great night's sleep depends on your preferences.
So is there anything we can do to help ourselves get a restful night's sleep if we are cursed with the hearing of a funnel-eared bat and a hyper-vigilant brain? The answer is slightly more nuanced than simply going on a quest for total silence. Many of our sleep preferences are determined by the kind of environments we are used to and that make us feel relaxed enough to encourage sleep.
For some, silence is awkward and disconcerting, for others like me, it's the holy grail.
Method 1: Reduce any noise.
If you prefer silence, the most obvious and easy solution is wearing earplugs. There are now many options available in a variety of materials from foam to silicone. Unfortunately for me, this is where one of my other super-senses, touch, interferes. After a couple of hours, the pressure of the ear plugs in my ear canal disturbs me. The following day it feels like I have a 'full' sensation in my ear which is hard to shake. However, for an uninterrupted afternoon power-nap or long haul flight, they are undoubtedly brilliant.
Method 2: Listen to something whilst you doze off
The next solution to consider is trying to blot out sounds and feel more relaxed whilst you doze off to sleep using something called binaural beats. This can improve your sleep and makes it less likely that you will be awoken by the slightest of noises.
Binaural beats are gentle musical recordings or soundwave therapies that are very much like simple, ambient chill-out music. There is actually a scientific basis to how these work to influence our brains. Whilst two different frequencies are played into each ear, the brain compensates by hearing a difference in the frequencies, or an 'illusory auditory stimulus'. It then tries to synchronise with this illusory frequency, altering our brainwave state. The particular frequencies in this music result in a deeper form of relaxation said to significantly improve the quality of sleep a person experiences. Since the frequencies played into each ear are different, it requires stereo headphones to work effectively - which is unfortunate for me and my super sensitive lug-holes! After dozing off peacefully I was disturbed during the night by having to remove the ear phones.
Method 3: Play something that makes a constant and steady background noise.
Remarkably, playing a constant background noise which blocks out the unwanted sounds that keep you up at night may just be the ultimate solution. For someone such as myself who enjoys silence, this seemed the least appealing of my options. It turns out, not all 'silence' is defined by the complete absence of noise.
Enter: white noise. You may consider white noise to be the kind of fuzzy, static sound heard when there's no signal on your television or radio. It is in fact combination of all the different tones the human ear can perceive, up to 20,000 to be precise, played at the same time. These produce a continuous sound that is so multi-layered and indistinct (usually a ‘hissing’ or ‘shushing’ sound), that the brain begins to ignore it. It literally fades into the background taking other external sounds with it. Many of us find being out in nature so peaceful for this very reason: the wind blowing through the trees, the patter of rain and the gurgling of rushing water create so many sound frequencies we perceive them as white noise, hence theses sounds are included on many white noise players.
Fighting noise with noise is precisely what I have found works well for me and brings me peace. There are of course numerous white noise options out there to buy, so it's best to research what you feel will work for you. I use an app called Lightening Bug which is not strictly a 'sleep tool' but allows the user to piece together various sounds to create a continuous soundloop. My night-time soundscape includes the hiss of pouring rain, the wash of gentle waves across a pebbly beach and the occasional slow rumble of distant rolling thunder. The thunder has been especially effective in helping me ignore the late-night sudden and sporadic slamming of car doors by tipsy patrons leaving the restaurant next door to where I live.
Ultimately, for this solution to work successfully, there are two requirements: Investment in a high quality set of speakers for your bedroom, and an understanding sleep partner. As well as drowning out the noises in your own room - cue no more nights listening to your partner's snoring - it becomes a sound automatically associated with sleep. Force of habit has meant that as soon as the speakers are on, I can't help but feel super sleepy.
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