Longman Dictionary of Contemporary English
Wiktionary
alt. 1 (context idiomatic English) Sleep before midnight, on the belief that early sleep hours conduce to health and beauty.John Stephen Farmer and William Ernest Henley, ''Slang and Its Analogues Past and Present'' (1890), p. 159. 2 (context idiomatic sometimes humorous English) extra sleep or a special nap. n. 1 (context idiomatic English) Sleep before midnight, on the belief that early sleep hours conduce to health and beauty.John Stephen Farmer and William Ernest Henley, ''Slang and Its Analogues Past and Present'' (1890), p. 159. 2 (context idiomatic sometimes humorous English) extra sleep or a special nap.
WordNet
n. sleep before midnight
Usage examples of "beauty sleep".
All of a sudden it occurred to him that this was not something Joshua would care to miss, beauty sleep or no.
That's our favorite way of not getting our beauty sleep, isn't it, dear?
I require my beauty sleep, and first I must have my olive-oil douche and bath.
Yet all the same this information astonished and irritated the count, coming as it did in the form of a simple note with an order from Kutuzov, and received at night, breaking in on his beauty sleep.
The weightlifters, trying to get their beauty sleep, were not amused to be roused by Rupert, roaring around the room, searching under beds, in the shower, even in the fridge.