It is a common experience that a problem difficult at night is resolved in the morning after the committee of sleep has worked on it.
Source: Recalled on his death 20 Dec 1968.
-- John Steinbeck, (Feb 27 1902-1968), US novelist; He aroused widespread sympathy for the plight of migratory farm workers in The Grapes of Wrath, 1939; won Nobel Prize, 1962.