Anecdotal story: I found on a vacation with no lights and no internet but lots of physical activity it just happened by itself.

Every night I fell into bed exhausted and slept deeply shortly after sunset. Every night in the middle of the night I woke up to go to the bathroom and wandered around for an hour or two like a Shakespeare character, then fell asleep for another shift until dawn.

Did not notice any effects besides being well rested from getting plenty of sleep which was unusual for me at the time.