It's the opposite of the more widely known "burnout", which is when an employee's mental health is affected by stress and an overwhelming workload.
According to Newsweek, Desnard likened his work conditions to a "descent into hell" and a "nightmare" which left him "destroyed" and living with "serious depression".
He claimed he had so few tasks "no one cared if I arrived at 9am or 10am".
"I had to buy some supplies – a few sheets of paper – and then my day was over," he said, adding he had been "deprived of his original responsibilities".
"I was ashamed of being paid for doing nothing," he said.
The publication also reported a colleague of Desnard told the court the situation was so dire his co-worker even contemplated taking his own life.
"Mr Desnard was fed up with doing nothing. This situation made him so depressed he talked more and more about committing suicide," the colleague said.
He ended up launching legal action after being made redundant in September 2014 after a "prolonged absence" caused by a car accident.
According to the Daily Mail, the tribunal found there was a link between the "deterioration" of Desnard's health and his work.
However, his former employer claimed Desnard failed to make them aware of the problem.
The case is the first of its kind in France, and has been described as a "watershed decision" which could inspire countless other underworked employees in similarly bleak situations to take action.
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Lifeline
: 0800 543 354 (available 24/7)
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Suicide Crisis Helpline
: 0508 828 865 (0508 TAUTOKO) (available 24/7)
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Youth services:
(06) 3555 906
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Youthline:
0800 376 633
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Kidsline:
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Whatsup:
0800 942 8787 (1pm to 11pm)
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Depression helpline:
0800 111 757 (available 24/7)
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Rainbow Youth:
(09) 376 4155
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CASPER Suicide Prevention
If it is an emergency and you feel like you or someone else is at risk, call 111.