- In the early 1990s, psychiatrist Thomas Wehr conducted an experiment in which a group of people were plunged into darkness for 14 hours every day for a month.
It took some time for their sleep to regulate but by the fourth week the subjects had settled into a very distinct sleeping pattern. They slept first for four hours, then woke for one or two hours before falling into a second four-hour sleep.
Though sleep scientists were impressed by the study, among the general public the idea that we must sleep for eight consecutive hours persists.
I've long harboured suspicions about this kind of simplistic advice. Anyone who has spent an extended period in the outdoors would have the same kind of suspicions. Activities like hiking and (wild) camping give a good behavioural baseline, particularly when exploring a route with no agenda. Thirst is addressed as it arises. Hunger does not come with the clock. Fatigue dictates rest - and if you've never fallen asleep of an afternoon in a bed of heather*, in the warmth of the sun, a gentle cooling breeze with only the sounds of bees or crashing waves to serenade you, you've really missed something!
The article contains this gem,
- "For most of evolution we slept a certain way," says sleep psychologist Gregg Jacobs. "Waking up during the night is part of normal human physiology."
The idea that we must sleep in a consolidated block could be damaging, he says, if it makes people who wake up at night anxious, as this anxiety can itself prohibit sleeps and is likely to seep into waking life too.
This is another reason why the paleo model so resonates with me. A paleo rationale certainly helped me conclude this some time ago. The BBC save the best 'till last,
- [T]he next time you wake up in the middle of the night, think of your pre-industrial ancestors and relax. Lying awake could be good for you.