Sleep disturbance
In western countries, sleep problems are a more and more common problem owing to lifestyle and environmental factors. Sleep disturbance is one of the most serious effects of environmental noise. More and more Europeans are exposed to noise levels above 55 dB(A) and 45% live in areas considered as uncomfortable for inhabitants.
Uninterrupted sleep is known to be a prerequisite for good physiological and mental functioning of healthy persons; sleep disturbance, on the other hand, is considered to be a major physiological noise effect.
In western countries, sleep problems are a more and more common problem owing to lifestyle and environmental factors. Sleep disturbance is one of the most serious effects of environmental noise. More and more Europeans are exposed to noise levels above 55 dB(A) and 45% live in areas considered as uncomfortable for inhabitants.
Measurable effects of noise on sleep begin at LAeq levels of 30 dB. Sensitive groups mainly include the elderly, shift workers, people with physical or mental disorders and other individuals who have sleeping difficulty.
Sleep disturbance from intermitted noise events increases with the maximum noise level. Even if the total equivalent noise level is fairly low, a small number of noise events with a high maximum sound pressure level will affect sleep.
Therefore, to avoid sleep disturbance, guidelines for community noise should be expressed in terms of the equivalent sound level of noise as well as in terms of maximum noise levels and the number of noise events. It should be noted that low frequency noise, for example, from ventilation systems, can disturb rest and sleep even at low sound pressure levels.
Special attention should also be given to the following consideration:
- Noise sources in an environment with a low background noise level. For example, night-traffic in suburban residential areas.
- Environments where a combination of noise and vibration are produced. For example, railway noise, heavy duty vehicles.
- Sources with low frequency components. Disturbance may occur even though the sound pressure level during exposure is below 30 dB(A).
- If negative effects on sleep are to be avoided the equivalent sound pressure level should not exceed 30 dB(A) indoors for continuous noise. If the noise is not continuous, sleep disturbance correlates best with LAmax and effects have been observed at 45 dB or less. Noise events exceeding 45 dB(A) should therefore limited if possible.
- It should be possible to sleep with a bedroom window slightly open (a reduction from outside to inside of 15 dB).
- Mitigation targeted to the first part of the night is believed to be effective for the ability to fall asleep.
