always wonder about the results of that type of study FS.

I mean, aren't the results tainted by the fact that they are garnered by testing on the type of person that would submit themselves to that type of testing?

For example, I've heard that if you sleep in a fetal position you are insecure and feel pressured in your life.

But maybe it is only the type person that lets himself be submitted to testing, that sleeps in fetal position, who is insecure. Maybe the rest of the world population who sleeps in the fetal position is actually quite confident and happy and wouldn't think of participating in sleep type testing.

Really successful people don't need the money these companies pay for the tests. Regular joes, who have a job, can't take the time out to submit to the tests. So their tests are skewed.

And, to elaborate on what WW said, I'm sure the results would be skewed for women depending upon age, and, well, time of month - so even if the charater was the same - the sleeping pattern wouldn't be.