From FinnegansWiki
A wink of sleep: a measurement of sleep, ie. "i didn't get a wink of sleep".
Winkle: the usual name in Britain for the common periwinkle, a mollusc often eaten in England. (Cockles are referred to on this page - cockles and winkles).
One can "catch" a wink of sleep and one can also "catch" food from the sea / river.
