An article in yahoo states about factors that cause stress in human beings.
http://in.lifestyle.yahoo.com/10-habits-contribute-stress-071639766.html
Amont them are lack of sleep, irregular meals, long hours of work, family/work place problems, no exercise, not giving time to self, etc.
In the name of getting in the eyes of bosses, some spend long hours at work place, sometimes even when there is no work. This reduces the time available to family members, affects the health in sitting idle for long hours without exercise, may be leading to commuting back to house in busy hours, no relaxation (spending time at office is definitely as good as spending the same at home), missing friends/relatives, etc. Similarly not having time for self like for leisure reading, entertainment, spending time in happy surroundings, etc will lead to stress buildup. Piling up of personal jobs due to more office work also increase the stress levels.
Spending time on internet without purpose also causes stress and after spending for few hours, we might have felt that we wasted our time without any gain. Further, sitting for long hours for surfing will also cause health problems due to sitting in same posture.
As recommended by experts, observing no phone / no internet / etc will bring some peace of mind. We should also take our leaves to be away from routine office works so that we can concentrate better rather than working continuously without even consuming our eligible leaves. This will also help the organization for which we are working. May be some shortsighted bosses think that the person on leave is not committed, but we have to take care of our health also.