The expression Sleep Tight is used very frequently throughout the English speaking world and means “to sleep very well.” Because it is so popular, many theories have been proposed as to its origin.

The most well-known of these is that the phrase originated when mattresses were supported by strings that needed to be pulled tight in order to ensure a firm mattress. However, this theory is highly unlikely.

Sleep Tight

Sleep tight

Another theory is that one needed to wear tight night clothes in order to keep out the bugs that were frequently found in the mattress. This theory is also not likely to be the source of this expression.

The most likely theory is that the word “tight” used to mean “soundlyproperly, or well.” Since this theory seems to correspond very well with the meaning of the phrase, it is the most logical and probably most correct explanation.

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