This is fascinating and worth a look, sleep being a key component of a healthy lifestyle and naturally a key component of the Paleo lifestyle.  And sleep having been entirely different in the days pre-dating the light bulb and access to "open all hours" technology.

Recently I have found myself wanting to sleep early and waking between 12.30 and 2 pm at night before going back to sleep, later.  I was unsettled by this, mostly, on reflection because we are told that good sleep is solid, uninterrupted sleep and "best" for eight hours and over.  That thought set up a judgment in me that I would suffer the next day due to a "sleepless" night.  In fact and whilst wrestling with that thought, it became apparent that it was that thought that was causing me the stress not the pattern of sleep cycle that I was experiencing.  It was a problem of perception!

This TED talk considers this and reminds us of numerous records through time of biphasic sleep patterns (sleep broken in two four hour segments) with the first beginning about two hours after night fall.  Separating the first sleep from the second sleep was a period of wakefulness for prayer, meditation or deep connection with a partner, the light being still dark outside and the connection pretty intense.

I found reference to this period of wakefulness shared by A. Roger Ekirch (a sleep historian) who recounts the tale of Robert Louis Stevenson and his biphasic sleep experience trekking through the French Alps in 1878.  Falling asleep shortly after sunset

"He awoke around midnight, smoked a cigarette, and, only after enjoying a hours contemplation, fell back asleep.  That hour, that "one stirring hour" moved him; Stevenson had never before experienced a "more perfect hour".  He had awoken not because of an interloper, a night terror or any other external actor but because of what he later described as a wakeful influence that goes abroad over the sleeping hemisphere and is unknown to those who dwell in houses"

So I am going with it.  Learning to drop the judgment that comes with thought and embrace this period of wakefulness and the sometimes unexpected pleasures that comes with it ;)

How about you?