(Reuters Health) – People who are exposed to wind turbine noise may have longer REM sleep latency and worse self-reported sleep than their counterparts who don’t have this exposure, a laboratory sleep study suggests.
The study included 24 participants who lived close to wind turbines, and a reference group of 26 individuals who didn’t live near wind turbines, who spent three consecutive nights in a sleep laboratory. The first night was for habituation, then participants were randomized to a quiet control and an intervention night with exposure to simulated wind turbine noise.
REM sleep latency was 16.8 minutes longer and REM sleep was 11.1 minutes shorter on nights participants were exposed to wind turbine noise, the study found. Other measures of objective sleep did not differ significantly between nights, including key indicators of sleep disturbance.
Results were similar for people with and without prior exposure to wind turbine noise.
“The findings indicate that continuous environmental noise with amplitude modulations may have some impact on sleep,” said senior study author Kerstin Persson Waye of the University of Gothenburg in Sweden.
“The impact of physiological measures were limited, and it suggests that the guidance limits for wind turbine noise that are currently lower than for transportation noise seem to be reasonable for protection of sleep,” Waye said by email.
Renewable wind power is crucial in reducing global reliance on fossil fuels. Wind turbines produce low frequency noise, which during the nighttime in particular propagates for long distances and into dwellings, potentially impacting sleep, researchers write in Sleep.
This study is the first investigation of wind turbine noise and physiologic sleep in a controlled environment, the study authors write.
To be included in the study, participants needed good hearing confirmed by hearing tests in the lab, and no history of sleep disorders or sleep medication use. People were prohibited from using alcohol during the study, but they were allowed to continue with their normal levels of caffeine consumption.
Noise was introduced into laboratory bedrooms through 88 loudspeakers mounted within the ceiling of each room. On wind turbine exposure nights, researchers played continuous synthesized wind turbine noise.
A sleep technologist scored results from polysomnography to determine sleep latency, REM latency following sleep onset, latency in first awakening, and total time in wake after sleep onset.
Researchers also measured cortisol, and found no significant differences between groups on nights with and without wind turbine noise.
One limitation of the study is that participants were recruited in part based on their prior complaints about wind turbine noise. Another limitation is that participants were not blinded to their exposure to wind turbine noise in the lab, which may have influenced outcomes particularly for self-reported measures.
Results from the lab may not necessarily reflect what would happen in the general population during a typical night exposed to wind turbine noise, said Dr. Jesper Hvass Schmidt of Odense University Hospital and the University of Southern Denmark.
“It is an artificial laboratory set-up where the exposure to wind turbine noise may be in the loud end,” Schmidt, who wasn’t involved in the study, said by email. “However, it is possible that you can find some dwellings where the exposure reach these levels during certain metrological weather conditions.”
Even so, a source of noise such as a wind turbine a can be a source of sleep disturbances and of annoyance, said Dr. David Hillman of the Centre for Sleep Science at the University of Western Australia in Perth.
“While not the subject of this study, some people have particular sensitivities to noise and are disproportionately affected by it,” Hillman, who wasn’t involved in the study, said by email.
“Given the choice, such people need to be far removed from wind farms,” Hillman added.
If noise is an issue and moving to a new house is not an option, abatement measures help, such as sound insulation of the dwelling, especially the bedroom, as well as shutting windows and wearing ear plugs at night, may help lessen the impact of wind turbines on sleep, Hillman said.
SOURCE: Sleep, online March 25, 2020. https://doi.org/10.1093/sleep/zsaa046
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