I'm about to try some insomnia interventions and I'd like to be able to use one of those gadgets that measures the quality and quantity of your sleep by measuring how much you're moving around etc. in bed. I don't have an iPhone or anything like that, so can't purchase an app (whatever one of those is ). Is there some standalone gadget that does this? Preferable a cheap and simple one? I don't need it to do all that other stuff that people use these things for (counting steps, etc.).