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Craving periods of uninterrupted time? A year without having to respond to emails? Tim Birkhead may be disappointed ("Lo, He created study leave", August).

Although study leave may enhance productivity, it can be too much of a good thing as monotony and isolation soon set in. Diminishing returns may also be a problem. Interruptions can be the grit that produces the pearl in the oyster precisely because they force us to break off. The result may be to curb the amount of effort expended on unprofitable possibilities and a return to work refreshed with new ideas.

Helga Drummond, Professor of decision sciences, University of Liverpool Management School.