The harm that is attributed to overwork is hardly ever due to that cause, but to some kind of worry or anxiety. The trouble with emotional fatigue is that it interferes with rest.
 Bertrand Russell, The Conquest of Happiness (1930). copy citation

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Author Bertrand Russell
Source The Conquest of Happiness
Topic fatigue trouble
Date 1930
Language English
Reference
Note
Weblink http://russell-j.com/beginner/COH-TEXT.HTM

Context

“Any person who has a great deal of intellectual work, devoid of emotion, to do - say, for example, elaborate computations - will sleep off at the end of each day the fatigue that that day has brought. The harm that is attributed to overwork is hardly ever due to that cause, but to some kind of worry or anxiety. The trouble with emotional fatigue is that it interferes with rest. The more tired a man becomes, the more impossible he finds it to stop. One of the symptoms of approaching nervous breakdown is the belief that one’s work is terribly important, and that to take a holiday would bring all kinds of disaster.” source