Can one of the Wakemate people please respond? First off, I love this product. But before I click purchase, I want to know: how good of a proxy is the wrist ac

Can one of the Wakemate people please respond? First off, I love this product. But before I click purchase, I want to know: how good of a proxy is the wrist accelerometer for brain wave activity? Someone else asked this already but I didn't see a response. Ideally, I would love to know what the quantitative results were from your testing. For instance, if sleepers rate their grogginess after waking up every day, what kind of an improvement do you see in those ratings? What is the distribution like? Are there a certain percentage of people who don't respond to the Wakemate because for some personal reason their wrist movements don't correlate with brain wave activity? I think this data would help sell a lot more of these since that's definitely what made me pause - and I was very ready to purchase. Thanks!