Sunday, December 18, 2011

Zeo vs. the motion sensors

I don't have a Jawbone UP. I tried to buy one earlier this month but Best Buy wasn't stocking them until the kinks have been worked out. Several of my friends rave about it, though:  it's just a bracelet that you wear and it automatically measures your activity, including your sleep.

The UP is one of a number of devices that try to measure sleep based on your movement in bed. It has a tiny accelerometer that picks up the slightest little twitches of your hand while sleeping. Since sleep phases are often accompanied by such movement,  (the theory is) software can later stitch it together to guess how much time you were in REM sleep or deep sleep. But these twitches are just a proxy for the actual sleep phase,  so I'm skeptical that it can measure it as accurately as the Zeo, which uses special sensors to directly detect the electromagnetic activity in your brain. Still, maybe it's "close enough", especially if (like me) you don't have any particular sleep issues that need analysis to the nth degree.

Movement detection is pretty easy, and there are plenty of ways to do it.  There's even an App for that! Smart Alarm, by Arawella Corporation, cleverly uses the built-in accelerometer, plus the microphone, to measure your movement at night and guess the amount of various sleep phases.

How does it compare to my Zeo Sleep Manager?  Last night I tried both at the same time and here are the results:

myZeo Personal Sleep Coach



Smart Alarm Sleep

Answer: Zeo is way better. It’s not even clear that the motion-detection app gave useful information, and might even be outright wrong.

The motion detection method was wrong. It says I:

  • Slept one hour longer than I did. (9 hrs vs 8)
  • Had more phases of REM sleep (6 vs. 4)
  • Had less deep sleep (5 vs. 8+)

Look at the charts and you’ll see the difference.

I don’t know how well this compares to an UP, but I bet the motion-detection systems just aren’t very useful.  If you really want to measure sleep, I say get the Zeo.

By the way, my recommendations:  Zeo comes in two forms: an alarm clock version that doesn’t require anything extra; and a more portable, cheaper version that plugs into your smart phone. If you have an iPhone or an Android, the Mobile Sleep Manager is a little cheaper and smaller.  The Alarm Clock version is nicer if you don’t already have a nice bedside alarm clock, or if you don’t like sleeping near your phone.