Are smartphones a blessing or a curse? Scientific jury's still out

Are smartphones really so bad for us? Hard science on the matter is hard to come by. Some studies, however, are starting to provide a few answers.

When companies hand out smartphones to their employees there is an implicit agreement that those staff are on call any time, any place. It can then be hard for them to detach and relax, says Arnold Bakker, a professor of work and organisational psychology at Erasmus University in Rotterdam.

In 2012, Bakker showed that heavy smartphone use caused more "work-home interference" - that is work encroached badly on home life. So far, so unsurprising. But he went on to show that this led to more burned-out employees. "It seems difficult, if not impossible, for mobile users to maintain a satisfactory balance between their work and personal life," he wrote in Applied Psychology.

Michigan State University researchers surveyed US workers and found that those who checked their smartphones for work reasons after 9pm were more tired and less engaged the next day.

Christine Grant at Britain's Coventry University surveyed remote e-workers at 11 major UK companies. She found that many found the technology helpful and that it allowed them to work more flexibly, while others suffered from the "always-on" culture, particularly frequent fliers who were contacted at all hours by colleagues in different time zones.

A Gallup poll in May found that stress levels in US workers were higher the more often they checked work emails on their smartphones out of normal hours. At the same time, workers who emailed most outside work hours rated their lives better than those who did not. Though more stressed out, the emailers saw their behaviour as proof of professional success and accomplishment, Gallup speculated.