This reminds me of an article I read years ago about how people used to commonly wake up in the middle of the night, before the advent of electric bulbs, and often get a waking period between sleep in two phases (I assume more in winter months than in summer due to daylight hours). Apparently it was a very popular time for writing by candlelight, and I'm sure the creativity enjoyed by some of this tendency toward hynagogia had plenty to do with it.