Back, Left, Stomach, Right

As I mentioned in an earlier post, I built an accelerometer circuit to record my body position while I sleep. The first few nights, I placed the device in my t-shirt pocket and secured it with a safety pin. That worked pretty well, but as my t-shirt loosened up, the device would fall away from my chest. I noticed this after looking at the data and seeing my position bounce back and forth between my left side and stomach.

For my second attempt, I took an elastic Velcro strap and attached the Altoids tin to it. I wear the strap around my chest and the device stays firmly in position. This has worked surprisingly well. The elastic strap gives a little when I breathe, so it's not uncomfortable to wear. Two small pieces of Velcro are the only thing holding the tin to the strap.

Do not wear this through airport security

My device records raw X, Y, Z data from the accelerometer, which I later analyze with a Ruby script. The script outputs a line each time by body position changes. It also list of summary, showing how long I spent in each position.

I've  only collected data for the last few nights, but the results are already interesting. Some nights, I spend hours on my back. Other nights, I spend 20 minutes or less. The same goes for my stomach. Whether or not any of this correlates to my bruxism has yet to be seen. I'll post more results here as I get them.


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