That is the sound of a fake fireplace that I sometimes play on my real iPhone when I really

can't sleep. As a slumberer, I would give my performance a C. I sometimes have trouble falling

asleep, and I almost always have trouble staying down.

In my apartment, I've hung blackout drapes, stocked the pantry with melatonin,

and have tried every variety of self-hypnosis, trying to force quit consciousness.

When I'm on tour, I'll collect all of the hotel pillows and build a pyramid of them on my face,

trying to block out whatever it is that is keeping me awake at 5 a.m.

This is deeply human. I'm Dessa, and if you can hear the sound of my voice, then you are awake.

And I hope that's on purpose, that you're not just whiling away some exasperated minutes in the darkness,

the dreaded morning bird song looming ever nearer, trying to coax your rescue dog of a brain to do the

reasonable thing and come lie down for a while.

The question of those angst-ridden hours, and of this program, is why can't I sleep? We often hear that screens and

stress are to blame, but how much of our insomnia is really a product of the modern lifestyle? How much

and how well do humans sleep? And why does so many of us struggle with sleeplessness? Let's begin with a

little science. Let's talk body clocks.

I work very closely with Blind Veterans UK and these extraordinarily individuals who've lost

their eyes as a result of combat or disease. They're essentially time blind. Not only have they

lost their sense of sight, but they've also lost their sense

of time because the eye isn't able to detect the light-dark cycle and set the internal

master clock within the brain. That is Russell Foster, director of the Sleep and Circadian

Neuroscience Institute at the University of Oxford. And that term, circadian. It's the external light-dark cycle, particularly at dawn and dusk,

that is detected by specialized receptors within the eye,

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