If work is leaving you drained, try turning off your smartphone at lunchtime.
A study found that those who played on their phone during their lunch break were more tired during the afternoon than those who went for a walk or read a book.
This may be because they used up more mental energy - or simply because their eyes were strained or their necks were cricked.
The South Korean researchers said workers should be aware of the effect and employers should consider introducing "digital detoxes".
For the study, some 425 men and women were asked how they spent their lunch break and how they felt at the time and afterwards.
Roughly half spent their break on their smartphone, while the others enjoyed conventional activities such as chatting to a friend or going for a walk.
Both groups said they felt they had switched off from work over lunch.
However, those who had played on their phones didn't feel as rejuvenated afterwards. They were more likely to say the felt "used up", "burned out" and "emotionally drained" as the day went on.
The researchers, from the Korea Institute for Research and Behavioural Sciences, said that multi-tasking on a smartphone by, for instance, listening to music while writing an email, can be mentally draining. Hunching over a small screen can strain the eyes, neck and shoulders, they wrote in the journal Computers In Human Behavior.
- Daily Mail