Marked by a lack of sleep: a sleepless night. (adjective)
Unable to sleep.(adjective)
Always alert or active; never resting: a sleepless district of the city. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "sleepless" in a sentence
"Certainly Aftermath took its toll in sleepless nights."
"Likewise, standing shackled and sleepless is not torture if the duration is short, but it is torture when the duration is 180 hours."
"But in so many married women sleeplessness and a consequent nervous condition are coupled with a lack of the complete sex relation, that one of the first questions a physician should put to those of his women patients who are worn and sleepless is whether her husband really fulfills his marital duty in their physical relation."