“Good night, sleep tight; don’t let the bed bugs bite.”
I’m sure many of us do, having heard it nightly as children when our parents flicked off the lights or have repeated it to our own children.
What does it mean?
“Sleep tight” means to have good, sound and restful night’s sleep.
Where did it come from?
As with many idioms, it seems there is a lot of speculation behind it’s true origin. With this particular idiom there are three possibilities.
In the “good ole days” beds were made having rope supports, rather than wooden slats, to hold the mattress for sleeping. The weight of sleeping would pull the ropes slack, the mattress would sag, and it would require tightening. Tight ropes meant a more comfortable and productive sleep. Hence, “sleep tight.” Many feel this most likely is not the original origin of the term.
This has more to do with the second part of the phrase, and the one I hated most as a kid, “Don’t let the bed bugs bite.” Bed bugs are wingless little nasties who live in mattresses and feed off of the blood of their sleeping victims. They can leave irritating bites but are said not to carry diseases (not that this is a great comfort). Back in the day, great lengths were taken to assure the beds remained bug-free. It was a common practice to set tin cans filled with liquid under the legs of the bed to create a moat so the little monsters couldn’t crawl up from the floor. Great care was also taken to assure a gap between the bed and wall and that no blankets or sheets touched the floor for the same reason, thus creating “a tight ship” of the bed. “Sleep tight” could be referring to this attention to detail but again it’s not the most likely possibility.
According to the Oxford English Dictionary: “It seems that tight in this expression is the equivalent of the only surviving use of the adverb tightly meaning ‘soundly, properly, well, effectively’.” Even though this possibility is a bit colorless and bland, it’s most likely the correct origin.
This idiom is also tricky when it comes to determining when it was first used. We have to rely on written word. One of the first uses found in print was in 1866. In her diary Through Some Eventful Years, Susan Bradford Eppes included:
“All is ready and we leave as soon as breakfast is over. Goodbye little Diary. ‘Sleep tight and wake bright,’ for I will need you when I return.”
Not many other citations have been found until the early 20th century and the Oxford English Dictionary lists none until 1933, by which time the innerspring mattress had been invented elimination the rope supports and possibility of origin #1. The phrase seems to have gained most of its popularity near the end of the 20th century.