About 420 million people, or 6% of the world's population, are addicted to the internet, according to a new study from researchers at the University of Hong Kong.

The meta-analysis, published last month in the journal Cyberpsychology, Behavior, and Social Networking, examined data from more than 89,000 individuals in 31 countries regarding the prevalence of internet addiction, which has been defined as an inability to control internet use, resulting in an adverse impact on interpersonal relations and physical health.

Internet addiction was more prevalent in countries or regions with a lower quality of life, which includes a low gross domestic product, and environmental factors such as high pollution and traffic. The highest prevalence was in the Middle East with a 10.9% internet addiction rate, while the lowest was in northern and western Europe with 2.6%.

“Internet addiction prevalence was higher for nations with greater traffic time consumption, pollution, and dissatisfaction with life in general,” the researchers wrote.

The researchers also noted that people may use the internet as a coping mechanism or an escape from the stress of the real world.

“In the present cyber age, people may immerse themselves into the virtual world of the internet to escape from stress they experience in the real world,” they wrote. “As the boundaries of the virtual and the real worlds become blurred, individuals who encounter more frequent real life problems have a greater motivation to use the internet as a coping mechanism.”