Constantly checking those work emails on your smartphone could be bad for more than just your marriage.

Heart problems, fatigue, and insomnia are among the consequences of failing to "switch off" from work at the end of the day, new research shows.

A study published in the journal PLOS One says that "work detachment" during leisure time is critical to staying positive and maintaining interest in your job. Employees who constantly monitor their smartphones for messages from work don't have time to let their "psycho-physiological system return to its baseline", the study claims.

The Employment of Britain survey canvassed 3,000 mainly white-collar employees who were mostly from the private business sector.

It revealed that 70 per cent of them reported thinking about work issues/worries sometimes when not at work. Results showed that 30 per cent of workers "often", "very often" or "always" think about work issues during their leisure time while 24 per cent are irritated by their inability to switch off when not at work.

Former Air Force reservist Demelza Challies, of Auckland, used to sleep with a notebook by her bed so she could write down ideas about how to do her job better in the middle of the night.

A solo mother who was also studying for a business degree, Ms Challies never watched TV and hadn't read a novel in over two years. "I'd never really switch off," she said.

With resources increasingly stretched by the move towards civilianisation, Air Force employees would take it on themselves to devote more of their lives to work, she said.

The job, which involved supplying Hercules aircraft, became a "never-ending thing".

"We didn't want it to be us who was the breaking point so everybody would just keep doing as much as they could."

Eventually it became too much and she quit the Air Force to take up fulltime study, but she still had trouble letting go.

Ms Challies sought help from life coach Kris de Jong, who helped her to develop strategies for managing her time. There were a number of simple measures people could take to help alleviate the issues with work/life balance, Mr de Jong said.

"If you have got a job that takes up a lot of your time and you have a family, make sure you schedule family time and work time, and try to separate them out as much as possible."

Personal circumstances play a role in how much time people should spend thinking about work, Mr de Jong said.

"If someone's priority was work or career at this stage of their lives, particularly if they don't have family, then I don't think there is any problem with it."

Down time

• Failing to switch off after work can be bad for your health

• Problems include cardiovascular issues, fatigue and interrupted sleep

• Employees who switch off in leisure time remain more positive and interested in their work