Employers are being urged to put smartphone policies in place before a test of work-life boundaries ends up in court.
Employment experts say smartphones and similar devices have now become an essential tool - but many employers have not caught up with fast-changing technology to put new systems and rules in place to prevent burn-out and protect confidentiality.
Tauranga Chamber of Commerce chief executive Max Mason said while smartphones offered gains in productivity, the devices had impacted on work-life balance.
Mr Mason felt it was "only a matter of time" before health and safety issues over the use of smartphones ended up in court.
"It's really important that employers start implementing policies that are guidelines about how employees should be accessing their phones," he said.
"It's a real cause for concern."
The chamber was in the midst of implementing a policy, Mr Mason said.
A tough job market in Tauranga is driving some employees to feel they need to be "switched on" at all times.
"I know of several people who are the sole earner for their family and desperately need their job. They are working all hours of the day and night to do their job well, so that if there is any merger or down-sizing they won't be first on the list to go."
Mr Mason recommended people feeling stressed about their workload speak to their employer, who might not have realised the effect of the smartphone use spilling into after-work hours.
"The employer has a duty to provide a safe and healthy work environment."
Mr Mason also advised working on time management skills and unsubscribing to emails.
Employment law specialist Rita Nabney also urged employers to put a smartphone policy in place, describing the devices as a "problematic area" throwing up several complex employment issues. When a worker took phone calls at home, it could cause issues over whether they could claim to be working and, if so, whether they were entitled to overtime or time in lieu.
Other factors included risk of breach of confidentiality when talking on a work phone at home, and being able to effectively work without tools at hand and while distracted by home life.
Mrs Nabney said work-life balance was important.
"We are seeing extraordinary levels of stress and then as a consequence, low productivity when people are stressed.
"There's an issue with productivity in the workplace if you are working long hours. You might be putting in the hours but you might be less efficient."
Counsellor Mary Hodson said smartphone use was having a "radical effect" on individuals and relationships. She regularly saw couples for whom it was a problem. "Smartphones mean that people are on duty all of the time until they switch it off when they go to bed - if indeed they do switch it off, some people don't.
"Even if you only get one call, you are still actually in work mode.
"I do feel concern for people who have to have the phone on them on their days off. Your mind is never away from work."
Mrs Hodson, emotion and sexual intimacy specialist with Achieve Health & Education Consultancy, said smartphone use was interfering with relationships for Tauranga couples.
"Quite a lot of people complain about the phone having to go on holiday with them and be answered and take the partner away from the holiday."
It's not just work - many people are using it constantly for non-work purposes, but with the same effect on relationships, she said.
Talk to your bosses about your workload if it's getting out of hand - they may not realise.
Switch your "out of office assistant" on at the end of the day and say when you will be able to respond to emails.
Switch off your phone when you go to bed at night.
Don't use it for playing - make time for your partner and family without the distraction of Facebook.
Negotiate with your boss to leave the phone behind when you go on holiday so you fully detach from work.