Sweet Dreams: Sleep App Reviews

Everyone talks about using the off-season to cross your "T"s and dot your "I"s. While my coach is loading me up on technique- and drill-heavy sessions, I'm trying to figure out how to balance the non-triathlon side of life—namely, rest, recovery and fueling. The biggest thing for me, and I'm sure for lots of other triathletes juggling a 9-to-5 (or as is often the case in my life, a 8am-7pm) job, is getting enough sleep. As a result, all of my off-season non-training training has been dedicated to becoming more efficient, figuring out how to plan/pack/cook ahead, etc. all in the name of more pillow time.

To track progress, I wanted to test out a sleep-monitoring device. Turns out the Zeo that everyone raves about is a little out of my price range, so I thought I'd test out one of the handful of iPhone apps that claim to measure your sleep duration and quality. After some searching, I narrowed down my top three to the following:

  • Sleep On It
  • Sleep Cycle
  • Sleep Time

And they all work in a slightly similar way: you open up the app right before bedtime, select your morning alarm and then hit some sort of start-button before lying the phone face down on your mattress, a few inches away from your pillow.

Then, using the iPhone's built in accelerometer, the app tracks any movement to determine whether you are awake, in light sleep or in deep sleep. All three also allow you to set an alarm window, which will then wake you up at what it determines to be the "peak" waking time within that window based on your light and deep sleep patterns.

The Verdict:

To start with, I was initially very skeptical about how effective a phone would be in tracking movement, and then translating that movement into periods of light and deep sleep. To test this, I ran a lot of the sleep apps at the same time using my old iPhone4 and my new iPhone 5, comparing the results of each. I would turn on both apps at the same time, set the alarms for the same time windows and then place them on approximately the same location on my mattress.

To my surprise, the graphs matched up. Here, you can see that Sleep Cycle (on the left) and Sleep Time (on the right) displayed relatively similar patterns of activities:

Okay, it's confirmed that the measuring itself was consistent across the apps, how about alarm times? Sleep Cycle and Sleep Time were the only apps that had the "smart alarm" so I set the two alarm windows for the same time. Again, across a few nights, I found that the alarms tended to sound within 1-5 minutes of each other. My guess is that they use similar software in determining when is "best" to wake up.

In the end, all it really came down to was 1) what metrics/features are available on each of the apps? and 2) how easy to use is the interface?

Sleep On It

I have to admit, I ruled this one out pretty quickly. Compared to the other two, it does not have a smart alarm feature and does not break the night down into periods of heavy/light/awake. Instead, using "Going to Bed" and "I'm Awake" buttons, it simply maps hours slept as a bar graph shaded in green/yellow/red to indicate the spectrum of green/good to red/bad [photo below, left]

Next, it looks like the app might do a good job of showing trends across time, but performs poorly when it comes to evaluating an individual night of sleep. "Sleep on It" displayed some interesting average/min/max stats, but in the end this really wasn't different than features provided by the other two. [photo below, center]

The one thing I did think was somewhat useful was the option to add any notes about the night or day before to your nightly sleep entry, but I know that's something I would never prioritize enough to do when first waking up. [photo below, right]

Final Thoughts: Basic, easy to use interface but lack of additional features and detailed reporting makes it hard to track any meaningful data.

iTunes link: Sleep On It

Price: Free

iTunes Grade: ★★★

My Grade: C+

Sleep Cycle

For starters, Sleep Cycle is very easy to use and has great tracking details. The alarm feature [photo below, left] was the easiest to use of the three, and made the alarm window extremely clear and easy to set. The nightly data output [photo below, right] was an easy-to-read graph and displayed general levels of activities. The only part of the nightly graph that I disliked was that it was not always clear how long these periods lasted for and I can only deduce that the plateau on the right image means a period of being awake.

That being said, not a lot is left to be desired with the cumulative output of that tracking. I found some of the data points a little meaningless (e.g. "Best Night", "Worst Night") and hard to toggle between individual days on the overall performance charts. To be honest, I probably could have done a much more thorough review of Sleep Cycle—particularly because several of the graphs required 5 days of data—but I ended up being much much happier with Sleep Time (see below) and cut my Sleep Cycle part of the experiment short.

Final Thoughts: Good nightly data, excellent alarm feature—but if you're trying to get a larger picture of sleep habits, not very helpful.

iTunes link: Sleep Cycle

Price: $0.99

iTunes Grade: ★★★★★

My Grade: B

Sleep Time

Like mentioned above, I fell for Sleep Time very quickly and have been using it nightly for almost the past ten days. The app won me over with its ease of use, larger number of additional features and superior data output.

Some of my favorite features are the simple add-ons that you would not expect. For example, when you first set your alarm, the app displays a countdown "time until alarm." [photo below, left]. This is great for people who might usually workout in the morning but may want to decide to push the workout to the P.M. if it would otherwise cut too much into their overall sleep hours.

Also appreciated is the "hold to wake" feature, great for people who might otherwise snooze and then go back to bed. In order to turn off the morning alarm, you actually have to hold down the button for three seconds before shutting off [photo below, center]. The only drawback to their hold versus snooze system is that it considers flipping the phone over to mean "snooze", which has led me to over-snooze on two occasions—but I'm pretty sure this is something you can change in the settings.

In the end, the biggest draw (or at least what I find most interesting to review when I wake up) was the depiction of light versus deep sleep shown in the nightly summary graph, paired with a breakdown of awake, light, deep+REM sleep. On the whole, it's a lot easier to use this app to infer sleep stages compared to the other two. In addition, the app then uses this data to calculate an "efficiency" score for the night. [photo below, right]. For example, I'm seeing pretty consistently that I am waking around the 3-4am time frame on a nightly basis and that I actually do have a better night's sleep (i.e. more cycles through REM, less 3am wake-ups) when I get more hours overall.

The one slightly deceiving thing to warn users about, however, is that a higher efficiency score does not always equal a better night sleep. For example, I have seen some 8-hour nights with an efficiency score in the 70%-range, while other 6-hour nights have scored up around 91%. From what I can tell, the efficiency score doesn't take into account overall hours—only what percent of X hours were you getting "quality" sleep.

There's also a "Soundscape" feature where you can set background noise on a timer (think waves, crickets, etc.) that looks interesting, if you appreciate ambient noise while falling asleep. You can also set it to any of your iTunes playlists if you prefer not to fall asleep to "A night in the Amazon forest with birds and crickets."

Finally, for kicks, I ran the app after Thanksgiving dinner, with lots of food/drinking/sweets. Dead as a doornail, in a food coma:

Final Thoughts: If you're going to track sleep, this gives you the best overall snapshot of each individual night, as well as the cumulative effects. The highlighting of total duration, wake-up time and the efficiency score make it more about a challenge to get a better night's sleep than just recording data—though it does a pretty stellar job at that as well. 

iTunes link: Sleep Time

Price: $0.99

iTunes Grade: ★★★★ 1/2

My Grade: A


Bottom line: the fact that I've stuck to Sleep Time for the longest (and still going...) is the biggest indicator of how simple and worthwhile it is to use for every-night tracking. Already I think using a tracking device like this has worked almost like a food log—just seeing how poorly I'm sleeping is enough to make me want to push a little harder to get in bed a few minutes earlier.

I would love to hear what everyone else thinks of these app or any others in the market (including Zeo). Do you think it's worthwhile to track sleep, or is it just another excessive data point?

Sweet dreams!