I'm obsessed with sleep. Of all the metrics that make up the quantified self, it's probably the one which most intrigues me, not to mention most confuses me. Until now, though, it's also been one of the toughest to accurately measure: wearable monitors wrapped around your wrist can themselves disturb your patterns. So, while ResMed's S+ observing you from your nightstand and doing entirely contactless sleep tracking might seem creepy or far-fetched at first, the potential usefulness could well exceed any weirdness about being watched. I donned my most fetching nightcap to test it out.