Possible Clues:

• When a second-shift employee may get home
• Possible starting time for a rave
• Late-night time
• When 'S.N.L.' ends
• Night owl's time
• Time after retiring?
• When 59-Across ends, in NYC
• Witching hour follower
• When 'S.N.L.' ends in N.Y.C.
• Early morning hr.