Several weeks back, in the thread at https://news.ycombinator.com/item?id=33561648 https://news.ycombinator.com/item?id=33561648 , I hit Google Scholar to find

Several weeks back, in the thread at https://news.ycombinator.com/item?id=33561648 https://news.ycombinator.com/item?id=33561648 , I hit Google Scholar to find seemingly relevant papers. Here are two showing negative productivity. The first is munitions production in England during WWI. There was linear production in hours worked, up to about 48 hours per week, then the marginal product went down; going negative after about 63 hours. See Figure 5 of "The Productivity of Working Hours", John Pencavel, 2014 at https://docs.iza.org/dp8129.pdf https://docs.iza.org/dp8129.pdf for a graph. On a more national level, "The effects of working time on productivity and firm performance: a research synthesis paper", Lonnie Golden (2011) at http://www.ilo.org/wcmsp5/groups/public/---ed_protect/---protrav/---travail/documents/publication/wcms_187307.pdf http://www.ilo.org/wcmsp5/groups/public/---ed_protect/---pro... points out: ] A recent analysis of 18, mostly European, Member countries of the Organisation for Economic Co-operation and Development explores the degree to which longer annual hours have been associated with per-hour productivity at the national level, since 1950. It finds that the responsiveness of per-hour productivity for a given increase in working time is always negative. Not only are there decreasing returns on added working time, the returns in the form of added production diminish more rapidly for longer working times. When annual working time climbs above a threshold of 1,925 hours, a 1-per cent increase in working time would lead to a decrease in productivity of roughly 0.9 per cent at the threshold and a fully proportional decrease of 1 per cent past the threshold of 2,025 hours (Cette et al., 2011).