Sleep trackers can tell us about the quality and quantity of our sleep, a product reviewer finds, but the devices can’t do much, if anything, about the sleep problems we may have.

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Few of us are satisfied with how we sleep; we all want more and better sleep in the hopes of improving our minds and bodies during our waking hours.

Technology holds out the promise of perfection. What happens when you’re out for the count? Are you sleeping poorly? Can you do better? Sleep-tracking devices use sensors to monitor and record the way you sleep in an effort to answer some of these questions.

But the reality of these devices comes nowhere close to the promise. After using yet another unspectacular sleep tracker — this time the much-anticipated Sense, which raised $2.4 million on Kickstarter last year — I was reminded, again, of how fundamentally useless these devices can be.

The Sense works well enough, for what it is. It offers one primary advantage over most other sleep trackers. You don’t have to wear it or remember to keep it charged. Instead, it sits on your bedside table, watching what’s going on in your room. In my week of using it, I found a few flaws in the system, although several were pre-release bugs that should be ironed out soon. If you’re in the market for a sleep tracker, the Sense should be on your list.

But why are you in the market for a sleep tracker? Sleep tracking is a little bit bogus. I’m a terrible sleeper, but neither the Sense nor any other sleep tracker has revealed anything particularly helpful about what was happening to me between the sheets.

If you’re not sleeping well, you almost certainly know it already, and there’s a good chance you know why. At best, the tracker adds a layer of empirical precision to a situation already evident in your midafternoon yawns.

What do you do with its data? There are many potential reasons for your poor sleep — you’re working too hard, you’re partying too hard, you’re too stressed, you have insomnia, you have a baby, your neighbors are noisy — but the sleep tracker can’t fix any of those.

As I studied the Sense’s readings every morning over the past week, I was puzzled over what to do next. I knew I had slept poorly; I had gone to bed too late, woke up too early and I felt terrible. Why did I need a device to prove that?

The Sense comes in two parts that work more or less automatically. There’s a tennis-ball-size orb that sits on your bedside table. It remains plugged into the wall, wirelessly connects to the Internet, and it packs an array of sensors. The orb can measure the brightness of the lights in your room, temperature, humidity and the concentration of particulates in the air, and it can also record sound in certain cases, like snoring.

The other part of Sense is the Sleep Pill, a tiny, battery-powered device that attaches to your pillow and detects the movement of your body throughout the night. You can use two Sleep Pills with each Sense orb, letting you track your sleep and your partner’s.

The Sense orb, which has just gone on sale, comes in black or white, and sells for $129 with one included Sleep Pill. An extra Pill costs $39.

The Sense also has a well-designed app that works on newer iOS or Android devices. The app keeps a diary of your sleep and reports a daily score on how well you slept. The app also lets you set a “smart alarm,” which wakes you up when you’re in the phase of your sleep cycle most conducive to waking up, usually a few minutes before the time you set. This way of waking is supposed to make you feel refreshed, though not by much.

The main flaw in the Sense is that it misinterprets data from two Sleep Pills, my wife and I found. James Proud, founder of Hello, which makes Sense, said the company had an update coming soon to add algorithms that distinguish Sleep Pill movements when two are used, thereby solving the problem.

I’m inclined to believe him. But even if the Sense worked perfectly, I’m still not sure that many people need one.