Starving Dietitian

Counting Sleep for Sheep

You, in all truthfulness, are made of clocks. Every cell in your body has it’s own timepiece, most of them hard-coded by genes.

In fact, you have so many clocks in your body you have specialized cells just to keep the others in sync! The sum of their action is known as the Circadian Rhythm.

You’d think with all this timekeeping we’d have figured out why a third of our lives are pre-scheduled for sleep. Hundreds of thousands of dollars later and all we’ve really learned is that we have to have it.

So we keep sleeping. If you live to age 85 you’ve slept about 28 years of your life away. Probably double if you count sleeping in class.

So what drives our sleep/wake cycles? For the sake of simplicity I’m going to narrow it to two hormonal friends of ours.

Mellow Melatonin and Charismatic Cortisol.

Cortisol is one seriously misunderstood guy. People blame him for their unwanted weight, anxiety, and tiredness. Really he is an essential driving force for your body.

In small doses Cortisol revs up your metabolism and keeps you alert, say, when you’re on hour 8 of a 12 hour study session. However, just like a car driven too hard for too long, chronic elevation wreaks havoc on your body.

Melatonin on the other hand is our “knockout hormone”. Exposure to light keeps it at bay but as soon as the sun goes down it starts flooding our blood with sleepy thoughts. Which brings us to your rhythm.


Over a 24 hour period these hormones take part in a delicate ballet. One steps forward as the other steps back, a beautiful sight to see.

Another way to think of all this is that these hormones are the “batteries” for your clock.

AM Cortisol and Melatonin

When you wake up Cortisol is already flooding your body to jump-start your metabolism. The constant use of Melatonin during sleep has left it nearly empty, now ready to be shut off by sunlight and replenished. above

Noon Cortisol and Melatonin

By noon Cortisol is running at a slower pace while Melatonin is gradually replenished by the foods you eat.

Late Cortisol and Melatonin

Dinner is the final peak for Cortisol before it gradually fades for the day. Melatonin now has the upper hand as less light signals the start of release.

Sleep Cortisol and Melatonin

Cortisol is at it’s lowest around 4am while Melatonin is in full force keeping you asleep. And so the cycle repeats.

Ever wonder why you wake up freezing but fall asleep sweating? The drop in cortisol at night sends blood to the skin to “shed” excess heat. The quicker you cool the quicker you fall asleep. In the morning the opposite is true as body temp and cortisol are at their lowest, pulling blood to the core and away from the skin.

So what does this mean nutritionally? Far more than you could imagine, but I’ll save that for Friday.

Until then, check out all the ways The Rhythm affects you. Yes, even your bowel movements.


Be good to each other.

-J. Iufer


  1. Pingback: Sleep: The American Dream | The Starving Dietitian

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