"There can be no doubt that groups of industrial wind turbines ("wind farms") generate sufficient noise to disturb the sleep and impair the health of those living nearby," states Dr. Christopher Hanning in a recent report titled "Sleep Disturbance and Wind Turbine Noise."

Founder of the Leicester Sleep Disorders Service, which is the longest standing and largest service of its kind in Great Britain, Dr. Christopher Hanning's work in the area of sleep disorders has spanned thirty years. He currently chairs the advisory panel of the SOMNIA study, a major project investigating sleep quality in the elderly.

Dr. Hanning writes, "Sleep disturbance and impairment of the ability to return to sleep is not trivial, as almost all of us can testify."

He finds that wind turbine noise, even at levels that don't fully awaken us, may nevertheless take us out of the most restful stage of sleep and disrupt critical sleep cycles. Hanning says, "This sleep, because it is broken, is unrefreshing, resulting in sleepiness, fatigue, headaches, poor memory and concentration."

These are the most common complaints from residents of industrial wind farms and Dr. Hanning believes they are tied to disrupted sleep.

He states that current government and industry-sponsored research on wind turbine noise and sleep disruption have only used recalled and reported full awakenings as an index of the effects of turbine noise on sleep.

Because most of the sleep disturbance does not result in full awakening and is not recalled, it can't be reported. Dr. Hanning writes, "This approach seriously underestimates the effects of wind turbine noise on sleep."

Along with expected symptoms of fatigue, sleepiness and cognitive impairment, Dr. Hanning points to recent studies linking disrupted sleep to impaired glucose tolerance, increased risk of diabetes, increased risk of obesity, high blood pressure, heart disease, cancer and depression. He adds, "Sleepy people also have an increased risk of traffic accidents."

He cites research which found people are more easily annoyed by wind turbine noise at lower levels than that of aircraft, traffic or trains. "The noise of wind turbines has been likened to 'a passing train, which never passes,' " writes Hanning, "Which may explain why wind turbine noise is prone to cause sleep disruption,"

Hanning believes current research strongly indicates people can be negatively impacted by wind turbine noise at distances thought by the wind industry to be safe.

He cites a recent peer-reviewed study which follows ten families who have been so affected by wind turbine noise that they had to leave their homes, nine of them permanently.

"Of particular concern," writes Dr. Hanning, "were the observed effects on children, including toddlers and school and college aged children." The study found changes in sleep pattern, behavior and academic performance. Seven out of ten children in the study had a decline in school performance while exposed to wind turbine noise. School performance recovered after exposure ceased.

Dr. Hanning notes, "In total, 20 of 34 study subjects reported problems with concentration or memory".

American pediatrician, Dr. Nina Pierpont, who conducted the peer-reviewed study, now recommends a minimum setback of two kilometers or (about 1.25 miles) from homes, schools, and other inhabited structures.

George Kamperman, a distinguished American noise engineer and an industrial noise consultant with fifty years of experience, also identifies this setback. Says Kamperman, "The magnitude of the impact [of wind turbine noise] is far above anything I have seen before at such relatively low sound levels... we desperately need noise exposure level criteria."

Dr. Hanning also finds current calculated measures of wind turbine noise "woefully inadequate" and says he is unconvinced by what he terms, "badly designed industry and government reports which seek to show there is no problem".

He writes, "In my expert opinion, from my knowledge of sleep physiology and a review of available research, I have no doubt that wind turbine noise emissions cause sleep disturbances and ill health, "

Rather than relying on theoretical approaches to calculating distance, Dr. Hanning recommends setbacks based on observations of the effects on real people who are now living in or near operating wind farms.

He says, "...The only mitigation for wind turbine noise is to place a sufficient distance between the turbines and places of human habitation."

"Calculations cannot measure annoyance and sleep disturbance," he writes. "Only humans can do so."