Question: What does the phrase 'sleep tight' mean?
The phrase "sleep tight" is a way of saying "good night" and wishing someone a restful sleep. It originated in the days when beds had ropes supporting the mattress, and people would tighten the ropes to make the bed firmer before sleeping. Tightening the ropes would help ensure a comfortable and restful sleep. So, when someone says "sleep tight," they are wishing you a comfortable and peaceful night's sleep.