I always thought sleeping tight sounded kind of tense and not very relaxed, so I prefer "sleep loose". To the kids I will say "sleep sweet" or "sleep with angels".
But yours do not rhyme:
Good night.
Sleep tight.
Don"t let the
Bedbugs bite.
BTW, I do not know if this has anything to do with it. But, when my son was an infant, he was much more comfortable wrapped tightly in his blanket. If he wasn"t, he would not sleep well. I assume he became used to and was very comfortable in the close quarters of his mother"s womb.
Emmett
as docents at a 1750 historical home, we learned the origin of the term was from tightening the ropes on the bed frame. the rope frame held a straw-stuffed mattress and when the ropes loosened from use they used was a wooden key-like implement to tighten them...hence "sleep tight."