Worry about, as in It's too bad the experiment failed, but I'm not going to lose sleep over it. This expression, often put negatively, alludes to actual insomnia caused by anxiety. [First half of 1900s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use lose sleep over in a sentence
Do you ever lose sleep over those who killed themselves because you had invaded their privacy, or that of their loved ones?
"Oh, you make a great mistake if you think I'd lose sleep over any man," she said, with lofty coolness.The Mystery of Murray Davenport | Robert Neilson Stephens
There seemed to be no reason why both of us should lose sleep over the same cause.The Victory At Sea | William Sowden Sims