Sleep Tight Watch this on YouTube here - Sleep Video - YouTube Video Meaning: Sleep Tight means to sleep well, undisturbed. “Sleep tight” Origin: Sleep tight is quite a common phrase it's used in many parts of the English-speaking world. It's common at bedtime in the form of the rhyme "good night, sleep tight, don't let the bedbugs bite". The one piece of this phrase that gets a lot of questions is the word tight, there are several theories going around as to the origin of sleep tight. The most common suggestion is that the phrase dates from the days when mattresses were supported by ropes which needed to be pulled tight to provide a well-sprung bed. However, 'Sleep tight' didn't derive from ancient furniture and, in fact, isn't a very old expression at all. The word tight has a meaning of ‘safely’ or ‘soundly . So the phrase sleep tight meant to sleep soundly. The first citation of it that I can find is from 1866. In the diary by Susan Bradford ...