STRESS levels among smartphone users is increasing – leading to decreased productivity in the workplace.

That's the conclusion of a study into smartphone use by Amersham and Wycombe College lecturer Amir Khaki – who added high use of phones such as BlackBerrys creates greater anxiety.

Research carried out by the A Level Psychology lecturer turned up a story of one businessman having his BlackBerry flushed down the toilet by his wife as he spent too much time using it.

Mr Khaki studied the smartphone habits of a group of executives in middle to senior management who were either high or low frequency users.

He said: “People who used them frequently tended to have a distorted perception of just how many times they picked up their phone and equated this to being essential for the job.

“It is more difficult to complete a piece of work you might easily rattle off on a computer screen and the result is increased stress.”

Mr Khaki advised companies to tell their employees to limit the use of their smartphones.

“You need to know how to use it properly,” he said. “After all, we get training when every other technology comes online.

“The thing that causes people the most stress in life is not having control. Use your BlackBerry rationally. If you are on holiday, access it once every two days, explain to someone that you are away and you'll deal with it when you get back.”

In one example Mr Khaki observed a high frequency user trying to complete a simple spreadsheet. It should have taken about 20 minutes but ended up taking three times as long because of the number of interruptions due to the BlackBerry.

Suggesting a maximum of 12 hours use of a smartphone during the working week, Mr Khaki added the following advice: “At the start of any main task, turn it off. Interruptions don't help anyone do anything better, faster or at a higher quality.”