Sleep ranks right up there with weight in the pantheon of health issues to obsess over: Millions of people worry that they aren't catching enough ZZZs, or that the ones they are catching aren't high-quality.
Those numbers are far too large for gadget-makers to ignore. As a result, a growing number of devices purport to track, coach and improve sleep performance, taking advantage of the computing power of mobile phones and personal computers.
I've been trying out three of them: the Zeo Sleep Manager Mobile and Lark, both of which cost $99; and the $149 SleepTracker Elite. All use sensors that you wear to bed to measure how long and how well you sleep. They also feature silent alarms that wake you by vibrating, so you won't disturb someone else.
The most elaborate is the Zeo, which measures brain waves and eye-muscle movements to calculate how much time you spend in deep, rapid-eye and light sleep cycles, as well as how often and for how long you're awake in the night. The data is transmitted wirelessly to a free Zeo app on your iPhone or Android phone.
You wear the Zeo device positioned over the middle of your forehead and held in place by an elastic headband, which probably isn't compatible with any romantic plans you might have unless you're auditioning for the part of Jor-El in the next Superman movie.
While the headband didn't prevent me from falling asleep, I woke up the first night to find it lying on the pillow above my head. The next night it stayed on but I was so uncomfortable that I took it off myself in the middle of the night. Subsequent nights went better, though I still found myself aware of the device.
On the other hand, the simple Zeo app synced my data automatically, providing me with an impressive trove of information -- including my "ZQ," a single sleep score I could monitor over time to track my improvements. Even more analytics were available on Zeo's website, including a coaching regimen to help me improve my score.
The Lark sensor was much more comfortable. Like the Zeo, there's an elastic band -- but you wear this one around your wrist, where it monitors your sleep by tracking your movements during the night.
The Lark's data isn't as detailed as the Zeo. It did capture how many times I roused in the night and for how long, but it didn't break out the amount of time I spent in different phases of sleep.
The two devices also differ in how they wake you in the morning. The Zeo seeks a point around your designated alarm time when it senses from your sleep cycles that you're most likely to feel refreshed. The Lark, by contrast, transfers its data to your iPhone and starts vibrating at whatever time you set. The company says it concluded that users don't really like being awakened any earlier than they need to be.
The Lark, which also offers a sleep-coaching "pro" service for an extra $60, currently works only with Apple's iOS devices. An Android app is in the works.
The SleepTracker Elite was the least hassle to wear. Unlike the others, it doesn't require constant recharging. It's also the only one you might dare to wear in public: a slightly oversize, waterproof digital wristwatch that comes in white or black.
Balanced against those advantages is that it works only with a computer. You have to download and install its software to your Mac or Windows PC. Nor is it wireless; you transfer data from watch to computer via an included USB cable that clamps on to contacts on the back of the watch.
Programming the SleepTracker requires pushing lots of little buttons and navigating various digital-watch screens. Once I got it up and running, it did a good job of waking me and was able to capture my data -- though I did run into a bug in the Windows software that first prevented me from viewing my results, then concluded I had slept 17 hours. (If only.) The company says it is working on a fix.
None of these devices actually helps you get to sleep, at least not directly. The idea is that by providing you with data about yourself and offering various forms of encouragement, you'll adopt healthier sleep habits -- cutting out caffeine after 3 p.m., shutting off the computer and TV an hour before bedtime and the like.
That's the theory anyway, though you couldn't prove it by me. I had issues with all three. Frankly, I slept better without them.
Rich Jaroslovsky is a Bloomberg News columnist. The opinions expressed are his own.