I bought Sleep Cycle for my iPod touch because it sounded right up my alley. It uses the accelerometer in i-devices to measure how much you move while asleep to track your sleep cycles. Then it wakes you up when you will be most alert. How cool is that?

Well, it is pretty cool, but not because it tracks your sleep cycles, or because it wakes you up alert. First of all, sleep cycles are defined by brainwave patterns, not by movement. Perhaps it’s a decent analog–I’ve read that claim–but the charts that Sleep Cycle produces from my nights of sleep don’t look much like the examples of EEG readouts of sleepers.

Where in this graph was I dreaming? It looks like I fell asleep and woke up pretty abruptly, and was awake for a short period just after 6 am, but that’s all I can tell. I can also say that the app does not always catch it when you wake up. I’ve gotten out of bed to pee and not made a spike out of the sleep zone.

It is also not really useful for its primary purpose–to wake you up during the period that you will feel most rested. You set an alarm for the latest you want to wake up, and then a period of time during which it would be acceptable to wake up. The alarm is supposed to go off at the point in that period when you are moving enough to indicate that you are in shallow sleep. Supposedly, if it waited longer and let you go back into deep sleep, you would wake up groggy because of it.

Perhaps it’s just me, and perhaps it’s just that I’ve been in grad school, but I found that Inever preferred to be woken up before I really needed to be up. I did not notice any benefit from being woken up when I started to move instead of when I had just enough time to get ready for school. Luckily, you can set it for “normal alarm clock mode” with no “wake-up phase.”

Still, Sleep Cycle is cool for a couple of reasons. First, It tracks how much time I give myself for sleeping. It starts counting when you set the alarm at night and stops when you wake up and keeps track. That’s how I know, for example, that I gave myself an average of 8 hours and 35 minutes to sleep in for the 155 nights before Reanna moved to Eugene. (It doesn’t work with two people in bed.) (And that included my last 125 days of grad school–not too bad!) That means I averaged fairly close to eight hours of sleep a night, with an estimated average sleep latency of 30 minutes. And that brings me to the coolest part.

As a chronic, intermittent insomniac, I’ve always wanted to know how long it actually takes me to get to sleep. Now I have a pretty good idea, thanks to Sleep Cycle. Many of my graphs look something like this:

I started trying to sleep just after 1 AM and drifted off around 1:45. I probably would have told you that I lay awake for at least an hour. Here’s another:

That looks like about an hour of insomnia. Don’t be fooled by the little initial drop–that was me lying very still, trying to sleep, before starting to toss and turn.

To finish off, here are a few other graphs, just so you can see some of the variety:

(First published on August 29, 2011 on Nathen’s Miraculous Escape.)