It is well known that noise can interfere with sleep. Not only is the level of the noise important for sleep interference to occur, but so is its spectral content, number and frequency of occurrences, and other factors. Even very quiet sounds such as dripping taps, ticking of clocks, and snoring of a spouse can disturb sleep. One’s own whispered name can elicit wakening as reliably as sounds 30 or 40 dB higher in level [1]. Common sources of noise in the community that will interfere with sleep are comprised of all forms of transportation, including road and rail traffic, aircraft, construction, and light or heavy industry.
Noise interferes with sleep in two main ways: (i) it can result in more disturbed, lower‐quality sleep, and (ii) it can awaken the sleeper. Sleep has been studied extensively in the laboratory for many years and it has been found that there are several stages of sleep. A person passes from one stage to another during a night’s sleep. There are several ways of labeling these sleep stages or states. One common way is (starting from awake): rapid eye movement (REM), 1, 2, 3, and 4. The different stages of sleep can be detected by attaching electrodes to the body and monitoring brain waves and other behaviors. The REM stage has aroused much interest and it is in the REM stage that most dreams occur. Here the person has internalized his/her attention but is not in a deep stage of unconsciousness. However, paradoxically, in the REM stage a person is particularly insensitive to sound. Some studies have reported that it appears that sleep in Stage 2 is most easily disturbed while deep sleep in Stages 3 and 4 is least easily disturbed by noise. Some researchers [2] have suggested that while noise undoubtedly produces sleep patterns in people similar to those of a poor sleeper, a person compensates by spending more time in deep sleep, by becoming less responsive to stimuli and by napping. Thus, noise may not deprive a person of efficient sleep to produce an adverse effect on health. We must conclude that without further experimental evidence, we still cannot ascertain for certain that noise‐disturbed sleep has an adverse effect on health. However, we do know that sleep disturbance caused by noise will reduce a person’s feeling of wellbeing and that if this disturbance is sufficient it could conceivably have an adverse effect on health. Unfortunately, although there has been a considerable amount of research into sleep interference caused by noise, there is no internationally accepted way of evaluating the sleep interference that it causes or indeed of the best techniques to adopt in carrying out research into the effects of noise on sleep.
Also, little is known about the cumulative long‐term effects of sleep disturbance or sleep deprivation caused by noise. Fortunately, despite the lack of in‐depth knowledge, sufficient noise‐induced sleep interference data are available to provide general guidance for land use planning, environmental impact statements for new highways and airports, and sound insulation programs for housing. Some airports restrict nighttime aircraft movements and road traffic is normally reduced at night and is less disturbing but is still potentially a problem. Chapter 6 discusses descriptors used for predicting sleep disturbance caused by noise.
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