Time-wasting is not just an irritating habit. It is an affliction that ruins millions of lives and often requires therapy and other treatment for sufferers, psychologists have warned.

According to new research, one person in five now suffers from the problem so badly that their careers, relationships and health are threatened. Many researchers blame computers and mobile phones for providing too many distractions for people.

'The subject is seen as joke,' said Professor Joseph Ferrari of DePaul University in Chicago. 'But the social and economic implications are huge. These people need therapy. They need to change the way they act and think.'

Ferrari says that chronic procrastination is now so serious a condition it needs to be recognised by clinicians. In a study to be published later this year, he estimates that 15 to 20 per cent of people are chronic procrastinators. 'We now have data on 4,000 people, and it doesn't seem to matter what age you are, or your sex or background.'

He has devised a questionnaire to help diagnose the condition, which he says is 'much more common than depression or common phobias'. Procrastination also has knock-on effects - it encourages depression, lowers self-esteem, causes insomnia, and indirectly affects health by discouraging visits to the dentist or doctor. Sufferers are also more likely to have accidents at home involving unmended appliances.

Cognitive psychologist Professor John Maule, of Leeds University's business school, agreed that a significant proportion of the population were prone to procrastination, and argued that mood changes - particularly depression - might be to blame.

Research by Professor Piers Steel from Calgary University indicates that the incidence of chronic procrastination has risen dramatically in recent decades, from one person in 20 to one in four, as new technology has come to dominate our lives. Even the beeps notifying the arrival of email are said to be causing a 0.5 per cent drop in gross domestic product in the United States, costing the economy $70bn a year.

Ferrari, however, is less convinced that new technology is to blame for time-wasting. 'People have wasted time for centuries,' he said. 'Lots of people, particularly people who often have to work under time constraints, put work off because they kid themselves that they work best when under pressure, when there's a deadline.

'Studies have shown this isn't true. They're conveniently forgetting the times when it all went horribly wrong - and selectively remembering the odd occasion when things went well under severe time pressure.'

Once, humans probably did have stronger excuses for delaying chores that didn't need immediate attention, say brain scientists such as Alan Sanfey at Arizona University, whose work has shed light on the evolutionary origins of procrastination.

It appears that the brain is divided into two parts. One triggers 'automatic responses' which take precedence over everything else - such as fleeing sabre-toothed tigers. The other governs 'deliberate responses' - writing that report due next week or booking a visit to the optician. Evolution has dictated that the former take precedence. Today there aren't any sabre-toothed tigers, but we still put things off.