No. Night flights
are not restricted by any mandatory curfews, and most attempts to
legislate or regulate night flights have been struck down by the courts
as restrictions on interstate commerce.
In general, there
is less airline traffic at night because there is less passenger demand
for it. Many night flights are charter or cargo flights.
The FAA has taken
a small step in recognizing that night noise is more annoying and
disruptive than daytime aviation. Night time noise events are "weighed"
more heavily when noise contour maps are created.