The Trackers (Biofeedback)

The short version

• What they are: devices that measure something your body is already doing, like your heart rhythm, breathing or brain activity, and show it to you in real time so you can learn to shift it.
• Examples: Muse (a brain-sensing headband), HeartMath Inner Balance (a heart rate sensor that clips to your ear, with an app) and Lief (a wearable that tracks your heart rhythm and buzzes to cue slow breathing).
• What it feels like: nothing, physically. You're watching or listening to your own body.
• The evidence: heart rate variability (HRV) biofeedback has some of the better evidence in this directory. Brain-based neurofeedback for everyday stress is less settled.
• Best for: people who like data, people who quit meditation apps because they never knew if they were "doing it right," and anyone who'd rather learn a skill than rely on a gadget.
• Skip it if: tracking makes you more anxious, not less.

"Am I doing this right?"

Most of us have quit a meditation app at some point. Not because it was bad, but because ten minutes of sitting still with your eyes closed gives you no clue whether anything is happening. Is my mind wandering too much? Is this working? Should I feel something by now?

Biofeedback answers that question. It takes a signal your body gives off anyway, shows it back to you, and lets you see what changes it. It's less "trust the process" and more "watch the needle move."

How it works

Biofeedback has three steps: measure, show, learn.

• Measure. A sensor picks up a signal: your heart rate from your earlobe or chest, or electrical activity from your brain through sensors on your forehead.
• Show. An app turns that signal into something you can follow, like a color, a sound or a chart.
• Learn. You experiment with slower breathing, softer shoulders, letting a thought go. Over time you find what moves the signal, and eventually you can do it without the device.

That last step is the point. The devices in the Zappers and the Haptics act on your body. These teach you to do the work yourself.

Is this vagus nerve stuff?

Partly. Heart rate variability is one of the best everyday windows into your vagus nerve, because the vagus nerve is what slows your heart on each breath out. HRV biofeedback trains exactly that rhythm, usually by guiding you to breathe at about six breaths a minute.

Brain-sensing headbands like Muse are a different thing. They measure brain activity, not your vagus nerve. They earn a place here because they make meditation easier to learn, and calmer attention is part of calming your nervous system. Just don't let anyone tell you a headband is stimulating your vagus nerve. It isn't.

What the evidence says

• HRV biofeedback: a 2017 meta-analysis pooled 24 studies with 484 people and found that HRV biofeedback training was linked to a large reduction in self-reported stress and anxiety, including compared with control groups. Many of the studies were small, and self-reported results are softer than measured ones. By the standards of this directory, it's still a solid foundation.
• Brain-based neurofeedback: the research on consumer headbands is smaller and newer, and it isn't yet clear that the feedback beats ordinary meditation practice for everyday stress. Our Muse review goes into the details.
• Sleep tracking: consumer trackers are reasonably good at telling sleep from wake, and much weaker at telling sleep stages apart. Treat a "deep sleep" number as a rough guess.

For more on what HRV is and how to read it, see the Science and our HRV guide.

The catch: when tracking backfires

In 2017, sleep researchers at Rush University coined a word for a problem they kept seeing in their clinic: orthosomnia. Their patients had become so focused on perfecting their sleep scores that the worry itself was keeping them up.

If you check your ring before your texts, notice how the numbers make you feel. If a red score at 5:50am sets the tone for your whole day, the tracker may be doing more harm than good. The data should serve you, not grade you.

Who should skip this, or ask first

• Tracking makes you anxious. If the numbers become one more thing to fail at, start with the Analogs instead.
• You want something that does the work for you. Biofeedback is a skill. It takes regular practice, especially at first.
• You have a heart rhythm condition. Heart-based biofeedback is generally low-risk, but an irregular rhythm can throw off the readings, so ask your doctor what the numbers mean for you.
• You're in treatment for anxiety or insomnia. These tools can sit alongside your care. They aren't a substitute for it.

Try this tonight

You don't need a sensor to try the core skill. Breathe in for about five seconds and out for about five seconds, for five minutes. That's roughly six breaths a minute, the pace most HRV biofeedback trains you toward. If you wear a watch or ring that tracks HRV, see whether your overnight number shifts after a week of doing this daily. Just don't check it at 3am.

The bottom line

The trackers are the quiet overachievers of this directory. They don't promise to fix you. They show you what your body is doing and help you learn to change it, and the heart-based ones have some of the better evidence here. The trade-offs are effort and the risk of turning calm into another metric. If you like data and can hold it lightly, this is a good place to start.