Monday, February 28, 2005

Sleep Jerks

Have you ever had a "sleep jerk"? Just as you're starting to fall asleep, your body jerks and you wake yourself up. It's usually a one time deal. Besides waking yourself up, you might also scare the crap out of your spouse. I do that every now and then. Sometimes the jerks are quite strong. I had one of these last night.

These one time sleep jerks are called hypnic jerks -- the fancy medical term that keeps most people from understanding what physicians are talking about. As an aside, I always hear complaints from students about chemistry vocabulary. I call them secret code words that are used to keep the riff-raff out. If you didn't have special terms, anyone could understand what you're talking about and be a chemist. Apparently this sleep jerk phenomenon is more common when you're not getting enough sleep.

No one knows exactly why the body will sleep jerk. There are some theories. One theory is that as your body prepares for sleep, muscles start to relax. When the muscles relax, the brain interprets that as a situation where you might fall. The brain stimulates the muscles to catch you from falling and thereby creates a jerk. That's why these are sometime associated with tripping or falling dreams just as you're falling asleep. That's been my experience when I can remember what I was dreaming about. Sometimes it's hard to remember through all the expletives caused by scaring Dianne.

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