Urban legend has it that “sleep tight” referred to tightening up the ropes on the old-fashioned bed, but this is a myth perpetuated by historic house guides and visitors alike. The meaning of “tight” was a little different in the 18th century. According to the Oxford English Dictionary, one of its meanings was “soundly.” Another is “securely.” So “sleep tight” really just meant “Sleep well.”
Think about the expression “sit tight”–it doesn’t have anything to do with tightening the ropes on a chair, does it?
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Paul Boat 
History Myths Debunked 
Do you have any other source for this than that “tight” can mean soundly or securely? And how does it relate to “sit tight”? I have never heard “sit tight” nor understand its relation to sitting securely or soundly. Just the sound of it would make me think it was related to “hold your horses” or sit still or be patient. I can vouch that if your ropes on your bed aren’t tight, you don’t sleep well. Just wonder if there is more proof for your reasoning.
No, historians pretty much defer to the OED, although there is some more information from England at http://www.phrases.org.uk/meanings/sleep%20tight.html
As for the “sit tight” reference, I probably shouldn’t have thrown that in, but I meant to show that this other use of the word tight did not mean anything to do with ropes, it meant securely, in other words, sit still.
Interestingly I just was binge watching a bedroom series by Lucy Worsley on History of the Home the Bedroom. and they reference this very phrase tightening the ropes and also don’t let the bed bugs bite using wormwood sprinkled on the straw “mattress”. Could it be our friends across the pond have it wrong? (or right)
I clicked on your link and enjoyed watching the show. A wonderful British series! At around minute 10, the museum docent told Lucy that “Sleep tight” meant tighten the ropes. I believe they are mistaken, and that it sounds so logical that no one bothered to check with the OED on word origin.
‘Sit tight’ was a phrase my mother used when we were children to mean ‘sit in this spot and don’t get up until I tell you you can.’
Uh, oh I told that to someone a few days ago. I was told it meant to make sure the ropes were tight when I was on a tour of an historical home years ago. Guess I’d better tell my friend it’s an urban legend! Thanks for this blog. It’s really very interesting!
Hi, Mary– loved the bed post (little pun, there) and while I always took it in the sense you mention (sit tight) when I was growing up I began hearing the tight rope version from docents when I was a volunteer at a Colonial home, so thanks for setting that one straight.
Speaking of which (sort of), it immediately reminded me of another one I heard having to do with Colonial home furnishings — that the rooms were more multipurpose back then than they are now, furniture would be moved from room to room as needed and when a room was not in use would be pushed back against the walls (leaving the center of the room clear) and it is from that moving of chairs/furniture against the sides of the room after using it is where we get the expression and notion of “squaring a room away”.
Other than the general notion we carry of four corners indicating order and having “everything covered” (going to the four corners of the earth even when it is not rectangular) no other connection jumps to mind for me so my natural inclination of giving the benefit of a doubt to a plausible story wants to believe this one is so.
Your thoughts?
Thanks again so much — hope you have a great weekend.
Stephen Herchak
Hi Stephen! Thanks for the comments.
You are aware, I’m sure, that the pushing-furniture-against-the-walls story is long established as true. But I’ve never heard the expression “squaring a room away,” so I can’t comment on whether or not it stems from this practice. I think looking that up in the OED is unlikely to help . . . what word would you look up? Room? Square? I tried to look the phrase up in my two slang dictionaries, English Through the Ages and Cassell’s Dictionary of Slang, but nothing resembling “square a room” was there. Even checked Bartlett’s Familiar Quotations. Then I googled the phrase and came up with no hits. Sorry I can’t help.
Words and sayings from history usually have a practical background to them. Therefor to wish someone to sleep well would possibly refer to the bed set up properly, such as having the ropes properly tightened. A simplified dictionary definition often leaves out the historic and practical reason for the saying or term.