Some good answers to a similar question can be found here: https://www.reddit.com/r/AskHistorians/comments/6t1fnd/if_you_fell_into_a_coma_in_the_middle_age_what/

I wouldn't be so quick to jump from "fairy tale of magically extended sleep" to "definitely describing a coma." We're talking about a folk tale hidden inside the medieval equivalent of a fantasy novel here. And historical interpretation isn't just about pointing to things we think we recognize from today--it's about working from a medieval point of view and building up from there. Like, for example, knights who went to hell. But we’ll get there in a bit.

"Reading around" fantasy can be an important way to look for details of daily life. My favorite example is in Quest del San Graal, where as soon as any of the knights get to a castle, the first thing they do is take off their armor. But that's not what we're talking about with the Sleeping Beauty variant in the medieval romance Perceforest.

A fairy tale isn't a "myth to explain a scientific fact." In fact, Perceforest identifies the basic problem of long-term coma survival and says that they don't know how to solve it. "We don't understand how she's still alive, given that she's not eating or drinking anything. So it must be a pagan goddess helping her." (Venus, if you're wondering.) So...weeks and months, I'm not sure if there's much to be said.

For a handful of days, though? There's definitely evidence for how medieval Christians, at least, perceived longer-than-a-regular-seizure-or-fainting unconsciousness, and their reactions.

So now, our knight who went to hell.

The Vision of Tundale is a 12C account of a knight who was “almost dead,” and was taken on a voyage through various parts of the afterlife. The point of the text is “be religious, not just moral, or guess where you’re going,” of course. But the frame story concerns us here, rather than recalcitrant cows and bridges made of spikes.

Our Hero, Tundale, appeared to die, and before getting to the hell, purgatory, and heaven bits, the Visio sets the external scene:

He then committed [his axe] to the care of his frien's wife, saying, "Take care of my axe, for I am dying." Then, as far as the word has any meaning, his body immediately sank to the ground, separated from his soul; and his spirit was no longer of any account there."

The signs of death were present: his hair fell out, his forehead became hard, his eyes wandered, his nose became pointed, his lips grew pale, his mind failed, and his whole body grew rigid. The household ran, the food was removed, arms-bearers cried out, the guests cried, the body was laid out, the standards trembled, the clerk ran, the people marveled, and all the excited citizenry were disturbed by the death of this good soldier.

Why do we die? From almost the tneth hour of the fourth day to the same hour on Saturday, he lay dead with no signs of life remaining in him, except that those who tried diligently to coax his body back to life felt a little heat on his left side. Because of this warmth that they felt in this small part of him, they did not wish to bury his body.

So the first concern would be, is the comatose/whatever person actually dead, or just mostly dead? And since the verdict seems to be an ongoing case of “mostly dead,” they essentially hold a wake but delay the aftermath. However, it’s just a delay. After a week—warmth or not—they move to bury him. (Obviously this is when he wakes up.)

So it’s interesting that the text, for this little bit, focuses so much on people’s emotional or ritualized responses, rather than on Tundale’s body. The author’s goal is to emphasize how he was perceived as essentially dead, so in this case, it’s a reasonable interpretation that said author is reflecting familiar rituals surrounding death.

If you want gory descriptions of torments NOT in hell, we can talk about those, too. My main source base here—stories intended to make late medieval women look like a very particular type of saint—is...problematic, in terms of reading them as history, yes. But there’s still good reason to see some historical possibilities there.

So, one of the go-to criteria for women’s sanctity in 14-16C Christian Europe was to fall into ecstasies frequently, especially after receiving the Eucharist (the all-important, absolutely VIP Christian ritual of the Middle Ages). In some earlier saints’ biographies, called hagiographies, the description is left as such. By 14C-15C, however, there was an emphasis on going into further detail and proof—very much in line with the general course of intellectual development.

So the tl;dr here is that you have—in the context of these stories, remember—mostly men in a position of power enacting all sorts of bodily torment on ecstatic/non-present women to try to determine if they’re faking it. One of those times where it’s soooo tempting to do an anachronistic analysis…

Why is this still potential evidence for coma/mostly dead management? First, because of its role in the stories—designed to make the reader believe the womanreally is “gone.” Second, because medieval cases of catatonia—where the person is able to eat, drink, etc but can’t communicate with words or gestures—were treated similarly, albeit with a very, very different motive and descriptions of methods that are not nearly as gruesome.

So overall, it seems like medieval Christians perceived someone whose unconsciousness ranged well beyond sleep to be dancing between dead and mostly dead. They performed the rituals to take care of the person's soul and their feelings and societal expectations. But there wasn't much "care" of the body that could be taken besides watching over it and not burying it. But onlookers also seem to have made numerous attempts to wake up a person who "slept" too long--beautiful or not.