Having a smartphone or a tablet adds two hours to your work day. 

Researchers found that people work an additional 460 hours a year on average, as they are able to respond to emails on their phones. 

More than 90% of office workers have an email-enabled phone, with a third accessing them more than 20 times a day.

Nearly two-thirds say they often check work emails just before they go to bed and as soon as they wake up, while over a third have replied to one in the middle of the night.