Apparently, up to (and beyond) the Tudor period, it was common for people to have two sleeps. They would generally go to bed earlier than we do, but would then wake up in the early hours. They might light a candle and do some reading, or engage in a little light housework. Apparently this was also considered the proper time for sex.
After an hour or two, they would doze off again, and then get up at dawn (or before, if you were a servant).
It seems this only stopped being normal behaviour with the introduction of reliable artificial lighting (gas, and then electric), which allowed people to stay up much longer in the evenings.
The idea of 8 hours sleep a night is not normal, and has only been relatively recently introduced.