In the modern world the standard model of sleep is so-called “consolidated sleep” – meaning we go to bed and (try) to sleep in one straight shot of about eight hours until the morning. Waking in the middle of the night is seen as abnormal. But maybe sleeping straight through the night is the aberration.
There is some evidence that pre-industrial humans commonly experienced segmented sleep – meaning they would sleep for a few hours, wake for an hour or two, and then sleep the rest of the night. During the mid-sleep wakefulness people would engage in various rituals or activities such as prayer, meditation or reading, and was a common time for lovemaking. There were different names for the periods of sleep – sometimes called “dead sleep” and then “morning sleep” or “first sleep” and then “second sleep.”
If segmented sleep was the norm, the advent and use of artificial light is the primary reason we engage in consolidated sleep now. We go to bed much later than our pre-industrial ancestors and don’t have the time to have two periods of sleep punctuated by a period of wakefulness. In an experiment where people were deprived of all artificial light for a few weeks, many of them adopted segmented sleeping patterns.
So – if you wake in the middle of the night – don’t panic – you might just be experiencing a throwback to how our ancestors slept. Read, meditate, pray or engage in other activities – the second sleep will come.