Thursday, April 29, 2010

Get some sleep!

I found an interesting fact in the May 2010 issue of Oxygen: The average 135-pound woman burns 442 calories during eight hours of sleep. And my first thought was that such a fact seemed counter-intuitive. Get active, burn calories. Right? So how can we possibly burn that many calories while in our most inactive state? I decided to investigate.

First and foremost, I wanted to find a similar stat specific to men. Unfortunately, I could only come up with a general reference from WebMD that states the average individual burns 77 calories during one hour of sleep. There is no weight comparison like in the Oxygen stat, which makes me wonder, but it still reiterates the point that we're all sleeping off some calories. And so I continued my research.

Various websites describe sleep as a time of rest and repair, and they go on to say that it's the repair factor that burns those calories. While it may seem like our body is shutting down when we sleep, it's simply just relaxing so that it can fix what we've done to it throughout the day. And by that, I mean that our body restores energy levels in our muscles, works to strengthen our immune systems, repairs weakened cells, rejuvinates nerves...etc, etc. All of which requires energy. And energy comes from calories burned. For example, WebMD states that a pound of muscle burns 6 calories at rest while a pound of fat burns 2 calories at rest. (Heck yeah, muscles!) Physiologically speaking, I couldn't begin to tell you how that works, but it's pretty obvious that something is going on inside of us when we sleep. Like, for example, the fact that we're breathing. Or that our heart is pumping blood throughout our body.

And what is responsible for most of that activity? Our brains. There is a magazine called Psychology Today and I found an article on their website that claims our brains are responsible for 20% of all energy use. I'm sure that you've all heard of the REM stage of sleeping (rapid eye, dreams). It's at this point that we're in our deepest sleep, and it's also the point at which our brain is super active. All of its efforts to relieve stress, store memories and create dreams cause our breathing and heart rates to increase, our blood pressure to rise...sound familiar?

Sounds like a typical response to exercise. And we all know that exercise burns calories.

So there you have it. The reason we burn calories while at rest. Because our bodies are still hard at work, despite all evidence to the contrary. Now, it's not as great of a calorie burn as a solid sweat session, but a quality calorie burn still. So let it be known that I am not advocating that you replace gym time with bed time, just reminding you that getting good shut-eye is important. 


Unknown said...

I just got home from a presentation on the brain. You are right on! This doc from Grand Rapids ( said during the first 4 hours of sleep our body is physically repairing itself, and during the next 3 hours our brain, during REM, is repairing itself. No wonder I can't function without my 7+ hours!

Rebecca said...

Gooooooood thing I get 9+ hours a night here in Peace Corps! Just immmmaaaaagggginneeeee all the calories I am burning! haha.

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