Crossword Genius

What a drunkard might do to get an affectionate goodnight message? (5,5)

Ross

I believe the answer is:

sleep tight

I'm a little stuck... Click here to teach me more about this clue!

But I can't explain it at all! Could you help me understand?

(Other definitions for sleep tight that I've seen before include "I wish you a restful night" , "Get a good night's rest" .)

I've seen this clue in The Hindu.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.