Before you began learning to fly, defining the word “night” probably wasn’t hard. It’s when it gets dark, right? If only it were that easy in aviation (see "Here Comes the Night," page 28). The FAA, seemingly unable to make up its mind with these things, uses three separate and distinct definitions of that general time when the sun isn’t up and people are sleeping. FAR 1.1 defines night as “the time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the American Air Almanac, converted to local time.”
To maintain or regain currency, one must ignore this definition of night, and instead turn to FAR 61.57, which says that to carry passengers from one hour after sunset to one hour before sunrise, you must have completed three takeoffs and landings to a full stop during the past 90 days. That’s interpretation number two.
Finally, although you may be able to see well after sunset, the FAA says everyone needs to see you. That’s why, in FAR 91.209, it says you must have navigation lights, and they must be on from sunset to sunrise.
If you want to be really confused, learn to fly in Alaska. Night experience is hard to come by when the sun doesn’t set.