It is widely claimed that for the vast majority of human history, people slept in two distinct periods of time with a period of wakefulness in between. This is called "segmented sleep" or "biphasic sleep".
It was previously asked what the terminology is for this: Single word for the opposite of "nap" The question was closed for being unclear.
I've heard that various languages have historical terms to denote the two periods of sleep and the period of wakefulness between. I think I've seen "watch" and "vigil" used to denote the period of wakefulness between, but what were the two periods of sleep typically called?
For example, "After James awakened from his [first sleep period], he lit a lamp and studied an old book until he was ready for his [second sleep period]."