What does 'forty winks' mean?

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #73 [color=blue]“At the End of the Day (2)”, question 6

Forty apparently is the allowed for this kind of sleep.

(a) major
(b) majority
© maximum
(d) macrocosm

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #73 [color=blue]“At the End of the Day (2)”, answer 6

Forty apparently is the maximum allowed for this kind of sleep.

Correct answer: © maximum
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The forty in this sentence means minutes?
please explain
thank you

No, ‘forty winks’. It is a humorous comment. ‘Forty winks’ is an idiom for a nap, a short sleep.