Scientists from Swansea and Milan Universities found that people who have greater levels of internet addiction problems catch more colds and flu bugs than those who are less addicted to the internet.
The study evaluated 500 people aged 18 to 101 years old. It found that those who reported problems with over-using the internet also reported having more cold and flu symptoms than those people who did not report excessive use of the internet.
People with greater levels of internet addiction had around 30 per cent more cold and flu symptoms than those with less problematic internet usage.
Previous research has shown that people who spend more time on the internet experience greater sleep deprivation, have worse eating habits and less healthy diets, engage in less exercise, and also tend to smoke and drink alcohol more.
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These behaviours can harm their immune system and increase vulnerability to diseases.
The study suggested that those who are addicted to the internet may suffer from great stress when they are disconnected from the net, and this cycle of stress and relief associated with internet addiction may lead to altered levels of cortisol - a hormone that impacts immune function.
"It may also be that those who spend a long time alone on the internet experience reduced immune function as a result of simply not having enough contact with others and their germs," said Reed.
There were also differences in the way in which men and women use the internet - women using the internet for social media and shopping more than men, and men reporting more use of the internet than women for gaming and pornography.
"The results on internet usage, apart from being gender stereotypical, were not connected to its impact on immune function," Professor Roberto Truzoli from Milan University said.