"Taking work home can be deadly," the Daily Mail warns.
A small study of London-based office workers found those who reported being frequently troubled by work-related issues had patterns of heart activity associated with stress and anxiety.
Researchers interviewed 195 adults aged between 20 and 62 (70% male) about what they termed work-related rumination.
This was defined as how often a person was troubled by work-related issues when they weren't at work, measured on a scale of one (never/seldom) to five (very often/always).
Based on the responses, the researchers then selected 36 people, 19 of whom were scored as high ruminators (frequent worriers) and 17 who were scored as low ruminators (infrequent worriers).
On three consecutive weekday evenings, both groups wore a fitness band that combined a heart rate monitor and an accelerometer (a device that tracks physical activity) to look at their heart rate variability.
Heart rate variability is a measurement of the variability over time of the intervals between individual heartbeats. Reduced variability can be the sign of a "fight or flight" stress response being triggered.
Overall, the heart rate patterns suggested that the high ruminators were less relaxed than the low ruminators in the evening.
But despite the Mail's headline, this study certainly doesn't prove work-related thoughts are deadly. Short-term observations of a person's heartbeat cannot predict long-term health outcomes.
Nevertheless, it makes sense that constantly worrying about work can't be good for our mental wellbeing.
Read more about how to combat workplace stress.
The study was carried out by researchers from the University of Surrey in the UK, the University of Pisa in Italy, and Lillehammer University College and Oslo University in Norway.
No sources of funding are reported, but some of the authors declared being employees of a commercial company, BioBeats Group Ltd, which holds a patent for the devices used in this study.
While the Daily Mail's and The Sunday Times' reporting of the study was broadly accurate, both newspapers ran somewhat scaremongering headlines: "Taking work home is deadly" (The Sunday Times) and "Taking work home can be deadly" (the Mail).
This observational study aimed to see whether persistent work-related thoughts could be linked with changes in heart rate.
The researchers discussed the possibility that it's not the stress factor (stressor) itself, such as work, that may cause poor health, but the constant mental awareness of the stressor, even when it's not there.
This is called the theory of perseverative cognition – when individuals continue to experience unwanted mental thoughts related to a stressful situation.
This in turn causes constant physiological arousal, such as tension, sweating and a fast heart rate. Or, in layperson's terms, worrying a lot about something.
The researchers aimed to study this in a small sample of workers. This is useful for exploring the theory, but can't prove that thoughts about work caused the person's heart rate pattern or that, in turn, these changes would actually cause health problems further down the line.
The researchers recruited a sample of individuals working full-time in the financial sector, specifically for the bank BNP Paribas. The data was collected with the help of the healthcare insurance company AXA-PPP.
The full sample included 195 adults aged between 20 and 62 (70% male) who completed a questionnaire on work-related rumination.
Participants answered questions such as, "Are you troubled by work-related issues when not at work?". Responses were on a five-point scale ranging from "very seldom/never" to "very often/always".
The current study included a small subset of 19 high ruminators (32% female, average age 34) and 17 low ruminators (18% female, average age 33) who had full data available.
They wore a monitor (Microsoft Band v2) paired with an application that measured heart rate.
This collected data on heart rate over three consecutive minutes (followed by a three-minute rest), with accelerometer data measured in 15-second bursts followed by a 45-second rest.
The researchers looked at heart rate data collected between 8pm and 10pm on three consecutive weekday evenings (Monday to Wednesday) when the accelerometer indicated the person was stationary rather than walking or running.
The researchers calculated the root mean square successive differences (RMSSD). This is a mathematical tool that has been well validated in measuring stimulation of the parasympathetic nervous system.
This system is the network of nerves that help the body wind down and relax, as well as regulate the functions of the digestive system.
A low RMSSD score would indicate someone was having problems relaxing in the evening.
Researchers did find RMSSDs were significantly lower in the high ruminators compared with the low ruminators, suggesting that the high ruminators were less relaxed in the evening.
There was no significant difference in the average heart rate between the two groups, and no influence from age or gender. Nor was there any difference in levels of participant activity.
The researchers observed that, as expected, high ruminators had lower heart rate variability than the low ruminators.
They said their findings "may have implications for the design and delivery of interventions to help individuals unwind post work and to manage stress more effectively".
This research lends support to the theory that people who persistently worry about work may be less relaxed in the evenings compared with those who don't think about work once they've left the office.
However, before we conclude too much from this research, there are several limitations to consider:
Nevertheless, it makes sense that being persistently stressed or worrying about work all the time can't be good for our wellbeing, if nothing else.
Technology can make it easier to work from home, but there is also the risk that work activities, or at least concerns about work, can invade our free time and cause both physical and mental distress.