“Not sleep a wink or not get a wink of sleep“ means not being able to go to sleep.

For example:

I hadn’t slept a wink on the flight and was feeling groggy and grumpy.

Our newborn son is rather colicky, so my wife

and I haven’t slept a wink the last few nights.

This was my first Grand Prix win of the season, and I was so 

excited I couldn’t sleep a wink that night.

The hotel was so noisy, I didn’t get a wink of sleep.

I didn’t sleep a wink last night because I was worrying 

about my driving test.

Tradução:

“Not sleep a wink” significa não conseguir dormir, não pregar o olho.