by OLINKA KOSTER, Daily Mail

Sitting in front of a computer screen for five hours a day can dramatically increase the risk of depression and insomnia, new research suggests.

Previous studies have focused on how too much screen time can cause physical afflictions, such as headaches, eye strain, and backache.

Now one of the biggest ever investigations into the hazards of computers in the workplace has concluded that they can also damage mental health.

In a three-year survey of 25,000 workers, many complained of feeling depressed, anxious and reluctant to get up for work in the mornings.

They were also plagued by broken sleep and reported problems getting along with fellow employees.

The study by researchers at Chiba University in Japan, concluded that bosses should limit the time their staff spend on computers.

Lead researcher Dr Tetsuya Nakazawa said: ' This result suggests the prevention of mental disorders and sleep disorders requires the restriction of computer use to less than five hours a day.'

The results, published in the American Journal of Industrial Medicine, showed one in four staff spent at least five hours a day at their terminal.

Once they crossed that threshold, the

dangers of psychological disorders setting in appeared to increase dramatically.

British experts said working alone at a computer for hours on end could lead to a sense of isolation, even in a busy office.

Psychology Professor Cary Cooper from the University of Manchester Institute of Science and Technology said concern was growing over mental health problems caused by working with computers.

'We are finding that people are working with machines as opposed to other people,' he said. 'The problem is not just sitting in front of a computer but the fact that people don't take a break and cannot prioritise what they are doing.

'They are overloaded then they worry about the work they are not doing.

'People are not interacting with each other and the longer you do that, the less work meets your social needs.'

Professor Brian Shackel, from Loughborough University, agreed: ' Even in a full office, the likelihood is staff would have targets to meet, so the opportunities for social chit-chat would be considerably diminished.'

Dr Nakazawa insisted the findings were not just due to staff being in repetitive jobs.

'They performed different types of work,' he said. 'The computers were different, as were the working environments. Even so, our results were extremely consistent over a three-year period.'

A spokesman for the Health and Safety Executive said bosses had a duty under the 1974 Health and Safety Act to protect the mental as well as physical health of staff, even though psychological damage was harder to prove.