Every human being alive wants a good night’s sleep, and given that it should (if done right) occupy a third of our entire lives, the business of getting a good night’s sleep ought to be one of the largest on the planet.
Which it why it’s a surprise that the launch late last month of the Lark system for the iPhone ($129), a wristband and app combo that tracks your sleep, hasn’t made a bigger splash. It feels like putting a watch on when you go to bed. But the plastic velcro-wrapped doohickey, which recharges on a tiny nightstand, is transmitting to your iPhone the whole time. The Lark app runs in the background on the iPhone, so your phone can be off the whole night. (Always a good idea to keep an iPhone plugged in when it’s running an app for seven or eight hours, of course.)
So what do you get in the morning? Well, the Lark can’t read your brain. It can’t tell you when you’re in REM sleep or deep sleep, which is a pity. But once you’ve strapped it on, the Lark is like Santa Claus — it sees you when you’re sleeping and knows if you’re awake.
How? Because the wristband is incredibly sensitive to tiny movements. It turns out that when we sleep, we’re as good as paralyzed. All those rolling over tricks we do at night are actually brief moments of wakefulness. And if you’re awake, you’re moving, if only slightly. Go ahead, try to keep your wrist perfectly still for more than a minute. Try pretending to be asleep. The Lark knows all. Or does it?