Today is World Sleep Day, but things do more than just bump in the night…

You may, or may not have heard that today is World Sleep Day. The event may sound like a bit of a snooze (sorry), but it highlights the importance of sleep in a world that never stops (worldsleepday.org).

Sleep disturbance caused by noise will affect most of us at some point in our lives, and it has been proven to be more than just an annoyance. Research carried out by cf. Berglund & Lindvall (1995) states that: “physiological effects can also be induced by noise during sleep, including increased blood pressure; increased heart rate; increased finger pulse amplitude; vasoconstriction; changes in respiration; cardiac arrhythmia and an increase in body movements”. It is also well documented that sleep disturbance can cause fatigue, depression and a decrease in performance.

Caused by lack of sleep?

But what is being done to reduce the impact of noise in homes I hear you ask?

For Acoustic Consultants, sleep disturbance must be taken into consideration as part of the planning application for a residential development. Usually, the guidance used in this type of assessment is taken from the ‘World Health Organisation guidelines to community noise 1999’. Specifically, one paragraph is often quoted on page 28 which states;

“For a good sleep, it is believed that indoor sound pressure levels should not exceed approximately 45 dB LAmax more that 10-15 times per night…”

Figures are also provided in the paragraph regarding limiting SEL values to 55-60 dBA for intermittent aircraft noise and providing an LAeq,8hr of 30dB for continuous noise (I bet you are feeling sleepy now).

This effectively means that the Acoustic Consultant will carry out a noise survey, measuring the average and maximum noise levels at the proposed residential development (or will use noise mapping software to predict levels at a number of properties). The levels are then used in facade calculations which provide sound reduction figures for glazing and natural ventilators (if required).

There is some ambiguity regarding what is meant by ‘not exceeding 45dB LAmax more than 10-15 times per night’. This is because it is not clear whether the WHO guidelines allude to individual events, or to individual measurement periods. This could mean that some bedrooms in new developments experience more events exceeding 45dB LAmax than others, depending on which interpretation is used. You can imagine that attempting to carry out this type of assessment without a qualified Acoustic Consultant could allow for some confusion, and has potential to cause problems.

At least until revised guidelines are produced, it should be left up to the Acoustic Consultants working on the developments to provide a robust assessment based on their knowledge and experience.

If you are reading this and would just like some quick, unofficial advice on reducing external noise, be sure to note the following:

  1. It may sound like your windows are made from tracing paper, but it is more likely that the window frame is the problem, or that you have a trickle vent that should be looked at first.
  2. ‘Egg boxes’ or anything of that ilk won’t do anything..so just no..
  3. Heavy curtains are unlikely to have a major impact, although they may reduce the reverberation (echo) in the room, which may help in some cases.
  4. Before purchasing any expensive ‘quadrupple’ glazing systems (I made that one up), ask for some advice from a professional consultant.
  5. Sleep well and remember to read this if you get bored of counting sheep.

1 Comment

Lynne McCandlish · 17th March 2017 at 7:03 pm

A topical read having experienced a poor night’s sleep in a hotel recently. The irony being that I was staying there as I was attending an acoustics conference the following day. On inspection the window frames were band aided (poorly) with obvious draught thanks to the cobwebs…

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