Thanks to Anne Dealy, Director of Education and Public Information at the Geneva Historical Society Geneva, NY, who sent this myth.
A recent study using reenactors showed that wearing corsets laced 3” tighter than natural reduced lung capacity by 2% to 29%. Some wearers felt short of breath but were easily relieved with rest. The conclusion: “Reports of corseted women fainting are likely to have been accurate,” especially during physical activity such as dancing. (See the excellent book, The Corset: A Cultural History, by Valerie Steele, 2003, for more info.)
So now we know that tightly corseted ladies were not faking the fainting spells, at least not all the time. But does it follow that fainting couches were invented and strewn about Victorian houses in case of sudden need?
In a word, no. According to the Oxford English Dictionary, the first known use of the word daybed is 1594, but the actual object dates much earlier. Paging through the Dictionary of English Furniture turned up many, many examples of antique couches and daybeds—most upholstered or caned—from the 1600s forward, proving that this item of furniture was not a Victorian invention. While the term “fainting couch” seems to date from the Victorian era (sadly, there is no listing of it in the OED), the style existed in ancient Roman, Egyptian, and Greek times. (below top Greek, middle Roman, bottom Egyptian) According to historians at the Smithsonian, reclining furniture like these examples originated in the 7th century BC with the Greeks and spread to the Romans. (see http://www.smithsonianmag.com/videos/category/ask-smithsonian/ask-smithsonian-why-did-ancient-greeks-and/)
Since the Victorians were fond of reviving historical styles—think Greek Revival, Egyptian Revival, etc.—the adaptation of those early pieces to current use was a fashion statement as much as a useful piece of furniture. As such, they probably would have been found in the most fashionable rooms of the house, like the parlor.