Investigate how noise affects sleep and human health

Sleeping safe is one of the most basic human needs for staying fit and maintaining bodily functions. How does hearing environmental sounds influence the quality of our sleep? Assistant Professor Junta Tagusari from the Laboratory of Regional Environmental Problems, Graduate School of Engineering, is studying the best method to measure noise and how it affects human health.

Unwanted sounds are classified as noise. Basically, all sounds can be classified as noise, especially if the noise has a negative impact on people’s lives, like environmental noise. Aircraft noise, road traffic noise and railway noise are classified as environmental noise. “

Junta Tagusari, assistant professor

During the day, in the general workplace, 60 to 70 decibels (dB) is considered the normal and tolerable sound range. In general, human ears are designed to perceive sounds twice as loud if the sound level is increased by 10 dB. However, during the night when most people are sleeping, the tolerance level for noise decreases. Tagusari referred to the report of the Regional Office for Europe of the World Health Organization (WHO) in 2018 which marked the threshold for nighttime environmental noise at around 40 dB at the level of building facades.

“Noise has the potential not only to damage hearing abilities, but also to cause broader health problems. The risk has been reported to be higher when noises are heard during sleep. The Regional Office report WHO for Europe also indicated that several chronic health problems, including heart failure and diabetes, may have been triggered by long-term exposure to noise-induced sleep disturbances, “he said. declared Tagusari. “Sleep disturbances are more critical than most people realize.”

This question, in fact, is not something new. The researchers concerned have reported several results. However, Tagusari felt that most of the existing noise indexes / indices, which use the average value of the sound level, are not sufficient to measure the effect of noise on sleep. He developed a new nighttime noise index based on data collected and analyzed in a 2014 study based on the sleep patterns of 30 adult subjects in Kadena, Okinawa.

Located in Okinawa Prefecture, Kadena Air Force Base is an active base for the United States Air Force. There are over 100,000 residents whose homes have been exposed to aircraft noise. Nighttime sound events around the base could measure up to 100 dB. The main source of bothersome noise in the study area are airplanes in flight, although in the front area of ​​the base noise is dominated by the taxation of aircraft noise. When the aircraft engine is left running for adjustments, it can produce a noise of 60 dB for several hours at dawn.

According to Tagusari, since the study period, the situation has not changed in favor of the residents. However, based on the analysis, Tagusari developed a new mathematical formula for the nighttime noise index, which could be applied to any noise-related epidemiological research. An epidemiological analysis on the health of the inhabitants around the Kadena air base has already been carried out, but it is planned to re-analyze the situation using this new index.

“These local residents have complained about airplane noises that occur frequently, even at night,” said Tagusari, the source of his research. “They took the initiative to ask our laboratory to measure aircraft noise and its correlation with their sleep. For a month, we not only obtained the nighttime noise level, but we also measured the body motility during sleep of some residents, aged 20 to 60 years. “

Tagusari admitted that a possible solution to avoid this type of problem appears to be to restrict the sources of environmental noise in residential areas. “Getting away from sources of noise would be great, but there are also promising alternative solutions for cases like this, namely changing flight schedules. The residents of the Kadena air base have brought the case several times before different courts, calling for the most ideal solution to reduce noise, but only received solutions deemed insufficient (payment of compensation, soundproofing installations). This problem, in fact, was shared by several residential areas in the vicinity of air bases across the country, but attempts to bring the case to court by the disturbed residents continue.

Given the almost ubiquitous existence of environmental noise, Tagusari is already planning and organizing further studies on noise and sleep. He is currently examining the effects of low-frequency noise produced by wind turbines in Wakkanai, Hokkaido, and how they disrupt the sleep of local people. In a separate research, Tagusari will apply the nocturnal noise index he formulated to determine the effect of noise exposure on fetal growth and low birth rate on women in Hokkaido.

“Assessing and mitigating the health risks posed by noise exposure is necessary to protect and maintain our healthy lives. It is the responsibility of researchers and the government, ”Tagusari said.