Noise from wind farms is no more disruptive to sleep than traffic sounds, new research has found.

A series of studies by sleep researchers at Flinders University has also revealed that very low-frequency wind farm noise is not audible to the human ear, either while awake or asleep.

In a project that took five years, more than 460 sleep study nights involving 68 participants were looked at.

Each person spent seven consecutive nights in the sleep laboratory.

They were recruited from four groups, including those living near a wind farm, those living near a busy suburban road and people living in quiet rural areas.

Each was played 20-second wind farm and road traffic noise samples repeatedly using three different sound pressure levels to compare their responses.

On a separate night, the study tested if longer three-minute noise samples, including very low-frequency wind farm sounds resulted in sleep disturbance.

The researchers found that short exposure to wind farm and road traffic noise triggered a small increase in people waking that could fragment their sleep patterns.

But it also showed that wind farm noise was no more disruptive than road traffic.

In the initial study, published in the Journal of Sleep Research in December 2021, researchers used an electroencephalogram (EEG) to analyse the brainwaves of 23 young healthy people while they experienced 3-minute samples of wind farm noise and road traffic noise played at different noise levels (33, 38 and 43 dBA).

“These noise levels span the approximate range of recommended maximum average indoor and outdoor noise levels at night,” said Claire Dunbar from Flinders Health and Medical Research Institute: Sleep Health.

“By noting changes in their brain waves, we found the participants responded similarly to both wind farm and road noise, especially when the sound was louder. Then, during light sleep, we found low-level wind farm noise caused a greater brain activation response, compared to road traffic noise played at the same noise level.”

However, the authors reported the effects of the sounds were brief, with most participants’ brain waves returning to baseline sleep activity levels 30 seconds after the start of each noise, with very few people actually waking up, either briefly or for a prolonged period.

“This tells us the overall impacts of the noise on the participants’ sleep was relatively small,” Dunbar said.

Last week, after the conclusion of the five-year program, Chief investigator Peter Catcheside told an international conference on wind farm noise in Dublin that the findings showed that both wind farm noise and road traffic noise disrupted sleep, depending mainly on how loud they were.

“However, at realistic levels, these effects were quite small,” he said.

“We also found no evidence to suggest that wind farm noise is any more disruptive to sleep than road traffic noise.

“At the highest exposure level, road traffic noise was a little more sleep disruptive than wind farm noise.”

Professor Catcheside said that while the study provided strong evidence that wind farms were not more disruptive, it did not rule out that people particularly noise sensitive might find it more difficult to get to sleep when noise levels were noticeable.

The final findings of the program are still to be peer reviewed.

– with AAP