Nearly 3 percent of Shanghai's middle school students suffer serious addictions to the Internet, allowing the Web to control their lives, according to the Shanghai Mental Health Center.

The afflicted youngsters have trouble concentrating and refuse to take part in any other activities except for sleep, said Du Yasong, an expert in psychology.

The findings were the result of a three-year survey among 3,600 students in 10 schools.

The study showed most students addicted to the Internet have trouble handling personal relationships, the Laodong Daily reported yesterday.

Yet, they experience a strong feeling of achievement in the virtual worlds they inhabit online.

Du said extreme addicts display abnormal behavior, including hurting themselves or others.

In one case, a 17-year-old student surnamed Hu woke up in hospital after sleeping for 29 hours. Before he fell asleep, Hu had spent 72 straight hours in an Internet cafe.

A recent visit to an Internet cafe in Hongkou District in the early hours showed that 40 percent of the terminals were occupied.

The users were mostly students who were chatting, playing online games or watching movies.

All of them looked alert, the newspaper said.

One student told the newspaper it only cost 10 yuan (US$1.46) to 15 yuan to remain overnight in the cafe.

Regulations governing Internet cafes say operating hours should be only from 8am to midnight.

But few Internet cafes seem to obey the rules. The cashier at the cafe in Hongkou District said about 20 people regularly stayed overnight, and the staff never asked them to leave.

About 4 million minors in China are addicted to the Internet, especially games, according to a report released during a session of China's legislature on Thursday, chinanews.com.cn reported yesterday.