Electric sleep: the gadgetry tracking and hacking the way we rest

As activity tracking goes mainstream, an arsenal of consumer technology is rolling out for sleep. But how much do these interventions help?

At 2.16am, I stumble to the bathroom. I catch a glimpse of myself. The light from the red bulb is flattering - I've been told to eliminate all blue light on my nocturnal trek - but the sleep-tracker headband, currently emitting the sound of gently lapping waves, kills any woke-up-like-this vibe. I adjust its double straps and feel my way back to bed.