Wiktionary
don't let the bedbugs bite
phr. (context idiomatic English) (non-gloss definition: Used to wish a person a good night's sleep)
Usage examples of "don't let the bedbugs bite".
Or, as another famous poet has put it, Sleep tight and don't let the bedbugs bite.
Nighty night, sleep tight, don't let the bedbugs bite, okay, Lewis?