I’ve been wearing a Fitbit Flex for about a month now. While wearing it I’ve learned that there’s a reason I feel wiped out after a busy Saturday running errands, that a busy workday is a bad fitness day, and that my sleep patterns are surprisingly varied. (I’m still trying to figure out what triggers a good night’s sleep.) Unexpectedly, the Flex also turned out to be a useful tool for enforcing my teens’ curfews; more on that later.Software is available for iOS and Android devices, so I loaded the mobile app to an iPod Touch. The app let me easily browse through my personal data, with more detail about synchronized data available on the website. Still, I needed more instructions, because the Flex was flashing various patterns of lights at what seemed to be random times. Clearly, the Flex was talking to me, but I didn’t speak its language.
I googled around and managed to find out that with a fast series of taps I can tell the Flex that I’ve either gone to bed or gotten up, which allows it to calculate how long and how well I sleep. If I forget to tap, I can add how long I slept later. (Clapping also sends the unit in and out of sleep mode, so I’ve learned to remove the band when attending any event likely to involve applause.) Two taps gives me a report on my progress toward my walking steps goal of the day in 20 percent increments, by illuminating one or more of the five lights on the Flex’s band. When I hit the 100 percent mark, it does a little happy dance of vibrations and flashing lights that’s surprisingly rewarding.
The Flex advertises battery life at about five days; I’ve been getting about six to seven days between charges, even though I rarely remove it (the Flex is water resistant enough to allow me to keep it on for my biweekly swim sessions).
There’s a low-battery warning in the app and on the website, which I’ve unfortunately missed a few times (as far as I can tell none of the flashing light patterns on the Flex itself indicate a low battery—at least not one I understand). Instead, I typically discovered my battery was dead when I tapped for a progress report and got no response. Fortunately, charging is pretty quick; I can plug it in after dinner, and it’s fully charged by the time I go to bed. The charger is a little bit twitchy, however, and once or twice it wasn’t actually connected when I thought it was charging. Syncing is easy; it happens in the background via Bluetooth when I get anywhere near the iPod Touch.
As with other tracking products such as Jawbone’s Up wristband, the app and the website allow you to track your food intake, log activities to get estimates of calories burned, track your weight, record your mood and health, and enter heart rate, blood pressure, and glucose readings. I was curious to see if simply wearing the Flex and looking at the data it gathered led to behavior change. It became very clear that sedentary days left me feeling more back pain and getting less sleep. I found myself heading out for a half-hour walk or so after dinner on days when I’d barely managed to turn on two lights (40 percent of my step goal) in the course of a day.
Finally, about that teen-curfew enforcer. I don’t wait up for my two teens; I give them curfews, and they wake me up when they come in. I try to look at my clock to make sure they’ve arrived on schedule, but I don’t always do that, and I think they know it. The Flex turned out to be a useful backup: The next morning I’d ask my kids what time they came in, and then I could check my sleep log to make sure it had registered a wakeup at that time. If I’d slept soundly until 1 a.m. when a teen had theoretically awakened me at midnight, clearly something was amiss.
With two bands on my wrist now, I find the one I really want to take off is my watch—which I would, if there were a little time display on the Flex. Maybe in the next generation.
Tekla S. Perry is a senior editor at IEEE Spectrum. Based in Palo Alto, Calif., she's been covering the people, companies, and technology that make Silicon Valley a special place for more than 30 years. An IEEE member, she holds a bachelor's degree in journalism from Michigan State University.