New research has revealed that internet addicts could be doing damage to their immune systems - making them more vulnerable to catching colds.

Spending too much time on the internet could damage your immune system, a study has found.

Swansea University's College of Human and Health Science found that people who have greater levels of internet addiction catch more colds and flu bugs than those who spend less time online.

Its research of 500 people, aged between 18 and 101, discovered that those who go on the web too much have 30 per cent more cold and flu symptoms than those who do not.

It also suggested that internet addicts may suffer stress when they are disconnected from the net and the cycle of "stress and relief" may lead to altered levels of cortisol - a hormone that impacts immune function.

Previous studies have 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.

The latest research was conducted by Professor Phil Reed and Rebecca Vile from Swansea University, Dr Lisa A Osborne from Abertawe Bro Morgannwg University Health Board, and Dr Michela Romano and Professor Roberto Truzoli from the University of Milan.

Prof Reed said: "We found that the impact of the internet on people's health was independent of a range of other factors, like depression, sleep deprivation and loneliness, which are associated with high levels of internet use and also with poor health.

"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."

The study found that people reported using the internet an average of six hours a day, but a sizeable minority used it for over 10 hours a day - most often connected with social media sites. There were also differences in the way men and women use the internet - women more for social media and shopping, and men for gaming and pornography.