These were the findings of meta-analysis and systematic review of 34 separate studies conducted by  Canadian, Swedish and Norwegian researchers and published recently in the British Medical Journal  (BMJ).

The studies included in this review covered 2,011,935 separate participants and compared the results of those who worked a regular 9-5 day, to those who worked evening shifts, irregular or rotating shifts, and mixed schedules.

In the UK, there are nearly 3.5 million shift workers – nearly 1 in 7 employees – so the results of this study suggest there are many people at potential risk. In the US nearly 15 million people work a permannt night shift or regularly rotate in to night work.

Shift work can cause profound disruption in a number of hormones that help regulate myriad body processes. According to lead author Daniel G Hackam, of Western University in Canada: “Night shift workers are up all the time and they don’t have a defined rest period. They are in a state of perpetual nervous system activation which is bad for things like obesity and cholesterol.”

Increased risk

Out of the more than 2 million participants of all of the studies, just over 25,000 had suffered from vascular events – an umbrella term for problems like heart attacks and strokes.

Amongst these people, 17,357 had suffered from some form of coronary event, 6,589 suffered specifically from a heart attack, and 1854 had ischaemic stroke due to lack of blood to the brain caused by a blocked artery.

The analysis found that these vascular events were significantly more common amongst those who worked shifts, than any of the other people.

Overall, those who worked shifts had a 24% higher risk of coronary events, 23% higher risk of heart attack, and 5% higher risk of stroke.

The largest increase in risk was found amongst night shift workers who had a 41% higher risk of suffering from a coronary event. Despite these increased risks, it was also found that there was not a higher risk of death, from any cause, associated with shift work. However major illnesses like this can have a devastating effect on quality of life for the rest of a person’s life, not to mention implications for the cost of care to the family.

Other reported risks

Other studies have been conducted on the negative health effects of shift work :

• A Japanese study measured the blood pressure of shift and non-shift workers at 30-minute intervals throughout their periods of work. Their results suggested that shift work increased the systolic blood pressure of their participants.
• A Harvard-led study published in PLoS Medicine found an extended period of rotating night shift work led to an increased risk of type-2 diabetes, mediated through the also increased risk of weight gain associated with working night shifts.
• Data from the ongoing Nurses Health Study has shown that women who work nights or rotate into night work on a regular basis are at increased risk of breast cancer due to the hormonal disruption night work causes.

Researchers at the University of California at Irvine and from the US Army tested the impact of email overload on 13 people in a suburban office setting.

Heart rate monitors were attached to computer users, while software sensors detected how often they switched windows. People with email switched windows an average of 37 times per hour. Those without changed screens half as often – about 18 times in an hour.

Multitasking is bad for the heart

Importantly, those who checked their emails more frequently were physiologically in what the researcher called a steady “high alert” state, with more constant heart rates. Those removed from email for five days experienced more natural, variable heart rates. Variable heart rate is a sign of good heart health.

The study was funded by the Army and the National Science Foundation. Participants were computer-dependent civilian employees at the Army’s Natick Soldier Systems Center outside Boston. Those with no email reported feeling better able to do their jobs and stay on task, with fewer stressful and time-wasting interruptions.

Speaking at the at the Association for Computing Machinery’s Computer-Human Interaction Conference in Austin, Texas, co-author of the study, UCI informatics professor Gloria Mark noted, “We found that when you remove email from workers’ lives, they multitask less and experience less stress”.  A five day break from email stress saw the heart rates of the participants return nor a normal state of variability.

Mark said the results suggested that “Email vacations on the job may be a good idea” and that the findings could be useful for boosting productivity. The only downside to an email vacation, she said, was that it was linked with feeling ‘somewhat isolated.”

The illusion of control

The problem of email stress has been noted in other studies. In 2007 a University of Glasgow study concluded that regularly checking emails was a kind of office worker’s plague associated that distorted our sense of being in control.

Amongst the 177 individuals in academic and creative jobs surveyed,  34% felt ‘stressed’ by the sheer number of emails and obligation to respond quickly. A further 28% were ‘driven’ because they saw them as a source of pressure. Just 38% felt ‘relaxed’ enough about emails to not reply until a day or even a week later.

Using monitoring software this study also found office workers typically switched applications to view their emails as many as 30-40 times an hour, for anything from a few seconds to a minute. While half the participants said they checked more than once an hour and 35% said they did so every 15 minutes.

Smartphones make it worse

Earlier this year UK researchers found that checking smartphones for e-mails and messages – outside of work – is linked with higher stress levels. In this study the most stressed people of all were those who were convinced the phone had vibrated or rung, alerting them to an incoming message, when it hadn’t (called “phantom alerts”).

Speaking at a British Psychological Society conference, author of the study Richard Balding said it was a serious problem for employee health and productivity:

“Smart phone use is increasing at a rapid rate and we are likely to see an associated increase in stress from social networking. Organisations will not flourish if their employees are stressed, irrespective of the source of stress, so it is in their interest to encourage their employees to switch their phones off; cut the number of work emails sent out of hours, reduce people’s temptation to check their devices.”

So what can you do?

Many aspects of work can be bad for your health including long hours sitting down and the long commute that some people have to get there in the first place. You don’t have to be a slave to email as well, and there are a few practical steps you can take to lessen email stress. Consider these tips:

1 If you get lot of junk mail – now is the time to unsubscribe.

2 Turn off the New Mail Alert pop-up or sound alert.

3 Reduce the frequency with which you check or update the inbox (set your computer to update every 20-30 minutes instead of 5 minutes, for example).

4 Use your preview function – to scan through email and decide what needs responding to and what doesn’t.

5 Get organised. Use folders to file and prioritise incoming mail and actions you need to take.

6 Don’t assume you have to respond to every email, respond immediately or even have the last word in an email thread.

7 Use filters and rules that come with your email software to mark things like subscriptions and newsletters as read as soon as they come in or to move them to specific folders to deal with later.

8 Talk to your co-workers. How often do end up sending an email to someone sitting a few yards away from you?

9 Turn your smart phone off at mealtimes, and weekends, at the gym, when shopping and on holidays… (you get the idea!).

That’s the conclusion of a new study which appears in the December issue of the Journal of Health and Social Behavior.

Under what is called a Results Only Work Environment (ROWE) programme in America, select workers at a popular discount store Best Buy’s headquarters in Minnesota have, since 2005, been able to change their work schedules based on their individual and family needs and responsibilities, without having to ask or even notify their managers.

The study’s key findings were:

•  Employees participating in the flexible workplace initiative reported getting almost an extra hour (52 minutes) of sleep on nights before work.
• Employees participating in the flexible workplace initiative managed their health differently: They were less likely to feel obligated to work when sick and more likely to go to a doctor when necessary, even when busy.
• The flexible workplace initiative increased employees’ sense of schedule control and reduced their work-family conflict which, in turn, improved their sleep quality, energy levels, self-reported health, and sense of personal mastery while decreasing employees’ emotional exhaustion and psychological distress.

The authors notes that while narrower flexibility policies allow some ‘accommodations’ for family needs, they are less likely to promote employee health and well-being or to be available to all employees.

“Our study shows that moving from viewing time at the office as a sign of productivity, to emphasizing actual results can create a work environment that fosters healthy behavior and well-being,” says researcher Phyllis Moen. “This has important policy implications, suggesting that initiatives creating broad access to time flexibility encourage employees to take better care of themselves.”

Researchers from Lund University in Sweden, looked at 21,000 people, aged between 18 and 65, who worked more than 30 hours a week and commuted either by car, train or bus, or were active commuters who travelled by walking or cycling.

‘One way’ journey time was compared to the volunteer’s perceived general health, including sleep quality, exhaustion and everyday stress. The results, published in open access journal BMC Public Health, showed that commuting by car or public transport, compared to walking or cycling, is associated with negative effects on health.

Lead researcher, Erik Hansson from the Faculty of Medicine at Lund University explained: “Generally car and public transport users suffered more everyday stress, poorer sleep quality, exhaustion and, on a seven point scale, felt that they struggled with their health compared to the active commuters.

“The negative health of public transport users increased with journey time. However, the car drivers who commuted 30-60 minutes experienced worse health than those whose journey lasted more than one hour.”

Hansson continued: “One explanation for the discrepancy between car and public transport users might be that long-distance car commuting, within our geographical region, could provide more of an opportunity for relaxation.”

This is because longer rural commutes were less likely to involve traffic jams and were more likely to be through green rural areas. For these users the commute also provided recreation in some form – a good reason to stay wedded to the car.

Hansson also noted that drivers who commuted over a longer distance tended to be men, and high-income earners, who travelled in from rural areas, a group that generally consider themselves to be in good health.

The study was unique because a mobile workforce is believed to help improve a country’s economy but the effects of commuting on the health of commuters and on the costs to industry in terms of sick days are largely unknown.

From a commuter’s point of view, the advantages of daily travel, such as a better paid job or better housing conditions, need to be weighed against adverse health effects such as stress, loss of sleep, low vitality mental health.