Sound: WHO Night Noise Guidelines

World Health Organization and Nighttime Noise Guidelines for Europe: Section 3.4 Wind Turbine Noise:  Recommend less than 40 dBA during sleeping hours.  Observed effects with 35 dBA. The WHO describes annoyance as a critical health effect, in that in some people it is associated with stress, sleep disturbance, and interference with daily living. Adverse health effects are observed at the level above 40 dB with environmental insomnia, self-reported sleep disturbance, and increased use of somnifacient drugs and sedatives.  At 50 dB hypertension and myocardial infarction.