Lol, that's total bullshit. Medieval peasants didn't work more than people today. And pre-medieval societies worked even less.

"One of capitalism's most durable myths is that it has reduced human toil. This myth is typically defended by a comparison of the modern forty-hour week with its seventy- or eighty-hour counterpart in the nineteenth century. The implicit -- but rarely articulated -- assumption is that the eighty-hour standard has prevailed for centuries. The comparison conjures up the dreary life of medieval peasants, toiling steadily from dawn to dusk. We are asked to imagine the journeyman artisan in a cold, damp garret, rising even before the sun, laboring by candlelight late into the night."

"These images are backward projections of modern work patterns. And they are false. Before capitalism, most people did not work very long hours at all. The tempo of life was slow, even leisurely; the pace of work relaxed. Our ancestors may not have been rich, but they had an abundance of leisure. When capitalism raised their incomes, it also took away their time. Indeed, there is good reason to believe that working hours in the mid-nineteenth century constitute the most prodigious work effort in the entire history of humankind."

Here's the good stuff:

Eight centuries of annual hours 13th century - Adult male peasant, U.K.: 1620 hours Calculated from Gregory Clark's estimate of 150 days per family, assumes 12 hours per day, 135 days per year for adult male ("Impatience, Poverty, and Open Field Agriculture", mimeo, 1986)

14th century - Casual laborer, U.K.: 1440 hours

Calculated from Nora Ritchie's estimate of 120 days per year. Assumes 12-hour day. ("Labour conditions in Essex in the reign of Richard II", in E.M. Carus-Wilson, ed., Essays in Economic History, vol. II, London: Edward Arnold, 1962).

Middle ages - English worker: 2309 hours

Juliet Schor's estime of average medieval laborer working two-thirds of the year at 9.5 hours per day

1400-1600 - Farmer-miner, adult male, U.K.: 1980 hours

Calculated from Ian Blanchard's estimate of 180 days per year. Assumes 11-hour day ("Labour productivity and work psychology in the English mining industry, 1400-1600", Economic History Review 31, 23 (1978).

1840 - Average worker, U.K.: 3105-3588 hours

Based on 69-hour week; hours from W.S. Woytinsky, "Hours of labor," in Encyclopedia of the Social Sciences, vol. III (New York: Macmillan, 1935). Low estimate assumes 45 week year, high one assumes 52 week year

1850 - Average worker, U.S.: 3150-3650 hours

Based on 70-hour week; hours from Joseph Zeisel, "The workweek in American industry, 1850-1956", Monthly Labor Review 81, 23-29 (1958). Low estimate assumes 45 week year, high one assumes 52 week year

1987 - Average worker, U.S.: 1949 hours

From The Overworked American: The Unexpected Decline of Leisure, by Juliet B. Schor, Table 2.4

1988 - Manufacturing workers, U.K.: 1856 hours

Calculated from Bureau of Labor Statistics data, Office of Productivity and Technology

https://groups.csail.mit.edu/mac/users/rauch/worktime/hours_workweek.html