TEDGlobal 2010

Jessa Gamble: Our natural sleep cycle

Filmed:

In today's world, balancing school, work, kids and more, most of us can only hope for the recommended eight hours of sleep. Examining the science behind our body's internal clock, Jessa Gamble reveals the surprising and substantial program of rest we should be observing.

- Writer
Jessa Gamble writes about sleep and time, showing how our internal body clock struggles against our always-on global culture. Full bio

Let's start with day and night.
00:16
Life evolved under conditions
00:18
of light and darkness,
00:20
light and then darkness.
00:22
And so plants and animals
00:24
developed their own internal clocks
00:26
so that they would be ready for these changes in light.
00:28
These are chemical clocks,
00:30
and they're found in every known being that has two or more cells
00:32
and in some that only have one cell.
00:35
I'll give you an example --
00:38
if you take a horseshoe crab off the beach,
00:40
and you fly it all the way across the continent,
00:42
and you drop it into a sloped cage,
00:44
it will scramble up the floor of the cage
00:47
as the tide is rising
00:49
on its home shores,
00:51
and it'll skitter down again right as the water is receding
00:53
thousands of miles away.
00:55
It'll do this for weeks,
00:58
until it kind of gradually loses the plot.
01:00
And it's incredible to watch,
01:03
but there's nothing psychic or paranormal going on;
01:05
it's simply that these crabs have internal cycles
01:07
that correspond, usually, with what's going on around it.
01:10
So, we have this ability as well.
01:15
And in humans, we call it the "body clock."
01:17
You can see this most clearly when you take away someone's watch
01:20
and you shut them into a bunker, deep underground,
01:23
for a couple of months. (Laughter)
01:26
People actually volunteer for this,
01:28
and they usually come out
01:30
kind of raving about their productive time in the hole.
01:32
So, no matter how atypical these subjects would have to be,
01:34
they all show the same thing.
01:37
They get up just a little bit later every day -- say 15 minutes or so --
01:39
and they kind of drift all the way around the clock like this
01:42
over the course of the weeks.
01:45
And so, in this way we know that they are working on their own internal clocks,
01:47
rather than somehow sensing the day outside.
01:50
So fine, we have a body clock,
01:54
and it turns out that it's incredibly important in our lives.
01:56
It's a huge driver for culture
01:59
and I think that it's the most underrated force on our behavior.
02:01
We evolved as a species near the equator,
02:07
and so we're very well-equipped
02:09
to deal with 12 hours of daylight
02:11
and 12 hours of darkness.
02:13
But of course, we've spread to every corner of the globe
02:15
and in Arctic Canada, where I live,
02:17
we have perpetual daylight in summer
02:19
and 24 hours of darkness in winter.
02:21
So the culture, the northern aboriginal culture,
02:24
traditionally has been highly seasonal.
02:27
In winter, there's a lot of sleeping going on;
02:29
you enjoy your family life inside.
02:32
And in summer, it's almost manic hunting
02:34
and working activity very long hours,
02:37
very active.
02:39
So, what would our natural rhythm look like?
02:42
What would our sleeping patterns be
02:44
in the sort of ideal sense?
02:47
Well, it turns out
02:50
that when people are living
02:52
without any sort of artificial light at all,
02:54
they sleep twice every night.
02:56
They go to bed around 8:00 p.m.
02:58
until midnight
03:00
and then again, they sleep
03:02
from about 2:00 a.m. until sunrise.
03:04
And in-between, they have a couple of hours
03:07
of sort of meditative quiet in bed.
03:09
And during this time,
03:12
there's a surge of prolactin,
03:14
the likes of which a modern day never sees.
03:16
The people in these studies
03:19
report feeling so awake during the daytime,
03:21
that they realize
03:23
they're experiencing true wakefulness
03:25
for the first time in their lives.
03:27
So, cut to the modern day.
03:29
We're living in a culture of jet lag,
03:31
global travel,
03:33
24-hour business,
03:35
shift work.
03:38
And you know, our modern ways
03:41
of doing things
03:43
have their advantages,
03:45
but I believe we should understand the costs.
03:47
Thank you.
03:50
(Applause)
03:52

▲Back to top

About the Speaker:

Jessa Gamble - Writer
Jessa Gamble writes about sleep and time, showing how our internal body clock struggles against our always-on global culture.

Why you should listen

Jessa Gamble is an award-winning writer from Oxford, who lives in the Canadian Subarctic. Now that humanity has spread right to the Earth's poles and adopted a 24-hour business day, Gamble argues that our internal clocks struggle against our urban schedules. Her work documents the rituals surrounding daily rhythms, which along with local languages and beliefs are losing their rich global diversity and succumbing to a kind of circadian imperialism.

A dynamic new voice in popular science, Gamble was awarded a 2007 Science in Society journalism award from the Canadian Science Writers Association for her first-person account of daily life at the Eureka High Arctic Weather Station. She is the author of Siesta and The Midnight Sun: How We Measure and Experience Time.