Main Entry: sleep·less

Pronunciation: \ˈslēp-ləs\

Function: adjective

Date: 15th century

1 : not able to sleep <lay sleepless with fever>
2 : affording no sleep <sleepless nights>
3 : unceasingly active or operative <sleepless casinos>

— sleep·less·ly adverb

— sleep·less·ness noun