beauty sleep

sleep before midnight, assumed to be necessary for one's beauty.

any extra sleep.

Origin of beauty sleep

First recorded in 1855–60

You want your beauty-sleep, and you wont get it unless you are quick.

A Very Naughty Girl |L. T. Meade
Startled from her beauty-sleep, she sprang away like a hare, and scoured the plain in whirling circles.

Baby Jane's Mission |Reginald Parnell
If this mad scheme comes off you will need your beauty-sleep with a vengeance!

Joan of the Sword Hand |S(amuel) R(utherford) Crockett
I had missed my beauty-sleep, and my feet had frozen hard, but I was past regrets.

My Man Jeeves |P. G. Wodehouse

But there must be no beauty-sleep for the tired young girl who plied her needle.

Kidnapped at the Altar |Laura Jean Libbey

beauty sleep

informal sleep, esp sleep before midnight