My husband drew my attention to an article, How our ancestors used to sleep, which included an image of this window. I already knew that people went to bed at sundown and generally slept in two nightly stages (I've come across the phrases "first sleep" and "second sleep" as early as Chaucer and as late as Emily Brontë). What interested me here were a dog sleeping on the beds with its people and stained glass.
It delights me to have visual confirmation of a habit that dog-lovers could guess has a long history. A quick search of the web suggests that modern medical opinion is full of taboos and warnings against it (allergies! dominance!). But come on—we all know people and pet dogs like to snuggle up. If you want to put a dog asleep on a character's bed, feel free. For more on dogs in medieval Europe generally, there's a good article from History Today on line: The World of Medieval Dogdom. It includes the grumblings of moralists against women who pamper pets, but covers much more.
Meanwhile, a search for more the identity of the window led me to an item on Medieval and Renaissance Glass at 'The Art of Light' in the on-line journal Vidmus. Just think, an entire "online magazine devoted to medieval stained glass"!
The history and art of stained glass is a huge topic. My interests center on, first, medieval windows, and second, women artists in the late 19th and early 20th centuries. It's the latter who might provide inspiration for historical fiction. For leads, two articles seem to be good places to start: Women Stained Glass Artists and Stained Glass Stories: Women, Art, and Labor.