Graham Robb explains The Big Sleep that hit the pre-industrial world every winter:
Economists and bureaucrats who ventured out into the countryside after the [French] Revolution were horrified to find that the work force disappeared between fall and spring. The fields were deserted from Flanders to Provence. Villages and even small towns were silent, with barely a column of smoke to reveal a human presence. As soon as the weather turned cold, people all over France shut themselves away and practiced the forgotten art of doing nothing at all for months on end.In the mountains, the tradition of seasonal sloth was ancient and pervasive. “Seven months of winter, five months of hell,” they said in the Alps. When the “hell” of unremitting toil was over, the human beings settled in with their cows and pigs. They lowered their metabolic rate to prevent hunger from exhausting supplies. If someone died during the seven months of winter, the corpse was stored on the roof under a blanket of snow until spring thawed the ground, allowing a grave to be dug and a priest to reach the village.
The same mass dormancy was practiced in other chilly parts. In 1900, The British Medical Journal reported that peasants of the Pskov region in northwestern Russia “adopt the economical expedient” of spending one-half of the year in sleep: “At the first fall of snow the whole family gathers round the stove, lies down, ceases to wrestle with the problems of human existence, and quietly goes to sleep. Once a day every one wakes up to eat a piece of hard bread. … The members of the family take it in turn to watch and keep the fire alight. After six months of this reposeful existence the family wakes up, shakes itself” and “goes out to see if the grass is growing.”
It is unlikely this was hibernation in the zoological sense. While extreme cold might have set off a biological response normally seen only in squirrels, bears and marmots, human hibernation probably reflects a sensible, communal decision to stay in bed for as long as possible.
It’s hard to imagine living in a Malthusian world, where the marginal benefit of extra labor doesn’t justify the marginal cost in food energy.