There are a lot of social networking sites these days. In order to make relationships between people strong, sites like Facebook, Twitter and QQ have become a daily "must visit" site. In fact, many people spend all day in front of the computer or are busy with their phones only to spend time on these sites. Social networking sites provide facilities that enable people to communicate with their friends without spending time meeting them in person. In addition, they can play games. But what is quite surprising is that these sites not only give you pleasure, but can also increase risks of diseases in your body. Despite their primary purpose, these sites make people more isolated . "Sending a message through sites can cause side effects that are very big in the body's biological changes," said Dr Aric Sigman, a psychologist, according to DailyMail. Increased isolation may alter the workings of immune response  to the feelings of anger and others. People become angry easily. In the journal, Dr. Sigman says that it can increase the risk of cancer, strokes, heart attacks and dementia . Researchers found that the amount of time people used to meet face to face had decreased  greatly since the increased use of the electronic media in 1987. To save time, people prefer to meet virtually  rather than face to face; Education today even uses an online system that allows school-aged children not to come out of their rooms. Parents spend less time with their children, like the cases in England. The habit of having dinner together decreases, while the number of people who choose to work online at home increases. "The electronic media may also reduce the ability of children and adults in social interaction, as long as they are isolated. Social networking sites should help us improve the quality of life, but what happens is the opposite, they are not a tool to improve, but a tool to replace," said Dr Sigman. Social networking sites are harmful to users because   _  .
they fail to bring users the pleasure they want they don't bring users enough convenience more isolation is caused by less direct communication they have no effect on removing people's isolation