A short sleep; nap: He caught forty winks and perked right up(1828+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with forty-winks
A brief nap, as in There's just time for forty winks before we have to leave. This expression supposedly was first recorded in 1828 and relies on wink in the sense of “sleep,” a usage dating from the 14th century.