If you keep yourself tightly bundled you will sleep warm and rest well.
(nightly farewell) Good night.
Origin of sleep-tight
- There are many meanings of the word 'tight' and, unsurprisingly, there are several theories going the rounds as to the origin of 'sleep tight'. One 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.