pre-industrial slumber

I'm psyched to read that for the bulk of human history, polyphasic, or segmented sleep was the norm. It more closely resembles my own sleep cycle (when I'm left to my own devices & not working).

The two periods of night sleep were called first sleep (occasionally dead sleep) and second sleep (or morning sleep) in medieval England. First and second sleep are also the terms in the Romance languages, as well as the Tiv of Nigeria: In French, the common term was premier sommeil or premier somme; in Italian, primo sonno; in Latin, primo somno or comcubia nocte. There is no common word in English for the period of wakefulness between, apart from paraphrases such as first waking or when one wakes from his first sleep and the generic watch (in its old meaning of being awake). In French an equivalent generic term is dorveille ("twixt sleep and wake").

This period of wakefulness was often only semi-conscious, as the French term implies. It was highly valued in medieval Europe as a time of quiet and relaxation. Peasant couples were often too tired after a long day's work to do much more than eat and go to sleep, but they would wake later on to talk and make love.[3] People would also use this time to pray and reflect,[4] and to interpret dreams, which were more vivid at that hour than upon waking in the morning,[5] and even to visit. This was also a favorite time for authors and poets to write uninterrupted.

There is evidence from sleep research that this period of nighttime wakefulness, combined with a midday nap, result in greater alertness than a monophasic sleep-wake cycle.[citation needed] The brain exhibits high levels of the pituitary hormone prolactin during the period of nighttime wakefulness, which may contribute to the feeling of peace that many people associate with it. It is in many ways similar to the hypnogogic and hypnopompic states which occur just before falling asleep and upon waking, respectively.

...The modern assumption that consolidated sleep with no awakenings is the normal and correct way for human adults to sleep, leads many to approach their doctors with complaints of maintenance insomnia or other sleep disorders. Their concerns might best be addressed by assurance that their sleep conforms to historically natural sleep patterns.

PS: Wintertime hibernation in France.