The Paleobiology of Sleep


Until recently we thought that Matthew’s disrupted sleep was just another one of his symptoms.

Yet another broken thing that needed to be fixed.

Now we’ve learned that his pattern of sleeping for a few hours, waking for a while and then returning to sleep for another session toward morning is a natural sleep pattern for humans.

The Paleobiology of Sleep

In 1992, a century after the advent of electricity, Dr Thomas Wehr published the results a groundbreaking study which simulated wintertime conditions for ‘middle-latitude‘ humans before we had artificial light.

Study subjects experienced 10 hours of daylight in which they could do as they pleased. And then 14 hours of darkness.

When not unnaturally constrained by electric light, it turns out that the human sleep pattern resembles that of other animals. It’s polyphasic, meaning that it occurs in two or more phases within a 24-hour period.

Artificial light may have profoundly altered the pattern of our sleep, and we didn’t even know it.

The Paleobiology of sleepPreviously it was assumed that humans were fundamentally different from other mammals because of our preference for a single session of uninterrupted sleep. But Wehr demonstrated that when artificial light was removed, a consistent pattern of sleep and wakefulness emerged across study participants, involving two sessions of approximately four-hours of sleep interrupted by a couple of hours of quiet rest.

David Randall, in the New York Times, noted that at about the same time that Wehr was investigating the paleobiology of sleep, Roger Ekirch was investigating antiquated sleep patterns through ancient literature and historical documents. Like Wehr, Ekirch came to the conclusion that we used to engage in biphasic sleep by analyzing sources like the Canterbury Tales and old-fashioned advice that the ideal time for scholarship and contemplation lies between ‘first and second sleep’.

Primordial Sleep Patterns

For Matthew, the sleep-wake-sleep pattern emerged after he left his career in the aerospace industry on a disability leave due to illness.

At that time he also moved to the woods where he experienced less arthritis pain and reduced stress.

Now we can see that once his life began to more closely follow a primeval pattern, his sleep adjusted too.

Realizing that this change in his sleep may be a positive sign rather than yet another symptom, that it is actually a reversion to a more healthful template, changes things significantly for him.

How many of us are driven to distraction trying to do everything we can to get the uninterrupted sleep we believe we need?

There is no doubt that eight uninterrupted hours takes less time than an 11-hour sleep cycle with a three-hour intermission, but that mid-night interlude might have been important.

Nightly Meditation

In Waking Up to the Dark: Ancient Wisdom for a Sleepless Age, former Zen Buddhist monk Clark Strand explains that the period of quiet wakefulness that Wehr discovered between biphasic sleep resembles the state of consciousness of experienced mediators.

“This is a state not terribly familiar to modern sleepers,” Dr. Wehr commented after making this discovery, “Perhaps what those who meditate today are seeking is a state that our ancestors would have considered their birthright, a nightly occurrence.”

Which leads me to wonder: what happens to an entire species that may have meditated, quite naturally, for several hours each night and now no longer does?

To find out, we could look at the impacts of meditation.

Meditation & the Brain

One of the benefits of meditation is improved brain function.

Experienced mediators have different brains. Specifically, their brains exhibit “thickening of the cerebral cortex in areas associated with attention and emotional integration” according to the Harvard Gazette.

Dr Sara Lazar and other researchers determined that the differences in the brains of expert mediators could also be seen in non-meditators after just eight-weeks of mindfulness meditation practice. Neuroimaging documented significant changes in the structure of the new meditator’s brains in the areas associated with memory, sense of self, and empathy.

If we all used to be meditators in the wee hours of the night, as Wehr suggests, how would that have shaped our brains?

Could we be experiencing neurological changes as a species without even realizing it?

What if we have unknowingly diminished our capacity for attention, emotional integration, memory, sense of self, and empathy?

And what if the answer lies in allowing ourselves to return to a biphasic sleep cycle?

More specifically, the space in the middle of a biphasic sleep cycle, those quiet hours that Strand refers to as “a nightly meditation retreat for all Homo Sapiens on Earth.”


2 thoughts on “The Paleobiology of Sleep

  1. Pingback: 8 Areas for Health (Pick 1!) | petra8paleo

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