The list of indispensable gadgets that come with me every day, no matter where I am in the world, is a pretty short one. Most items on it are made by Apple: iPhone, iPad, MacBook. One is made by Fitbit: the Charge 2. One is made by Bose: wireless noise-cancelling QC30 headphones.

So far, so relatively mainstream. But then there's my one daily-use gadget you wouldn't be able to pick out of a lineup: the Muse headband, made by a Canadian startup called InteraXon. And now, saving a little room in my day bag, I carry the smaller, lighter, more versatile Muse 2.

When I first reviewed the Muse in 2014, I had no inkling it would become a central part of my daily routine. This meditation wearable (or "thinkable") was a fascinating novelty: with EEG electrodes on the forehead and behind the ears, it was able to give you feedback on when your brain was noisy with activity and when it was at rest.

Here, at last, was the holy grail for mindfulness practice and all the stress-busting health benefits it can bring: actual data on whether a given meditation session was effective in slowing the endless stream of thoughts that plague our brains.

Back then, however, the accompanying app took too long to connect and calibrate. When I meditated, which wasn't often enough, it was easier to listen to one of the popular mindfulness apps (such as Headspace, Calm or Buddhify) than to pull out the Muse and go through a cumbersome process that involved thinking of different categories of objects.

But the Muse evolved. A second iteration of the original headband, released in 2016, connected faster and had a longer battery life. The app became spiffier-looking and dropped the dumb category thing; now, to calibrate your level of brain noise, it asked you to "just be." Back in March, I used the Muse as the basis of a high-tech meditation contest.

Meditation evolves again

The Muse 2, confusingly enough, is the third iteration of the hardware (not counting the meditation sunglasses that InteraXon made for Smith Optics).

But even though it just looks like a smaller, slimmer version of its predecessors, the Muse 2 has been able to pack in more components — and represents a giant leap forward for the whole meditation wearable platform.

That's because the headband now features an accelerometer, a gyroscope, and an optical heart-rate monitor that tracks the pulse in your forehead.

The upshot is that the Muse app can offer Muse 2 owners three new kinds of meditation: one that uses those first two sensors, where you try to remain as still as possible; one that uses the pulse sensor to help you lower your heart rate; and one that employs all three sensors to take you through breathing exercises.

As of the Muse 2 launch, the offerings specifically for it in the Muse app are fairly bare-bones. There's only one kind of breathing exercise available (breathe in for four seconds, out for six), and just three introductory "lessons" in the heart meditation section.

But InteraXon plans on adding new lessons one by one after launch. Given the platform's evolution so far -- and the fact that it acquired a content company called Meditation Studio in July 2018 -- there's good reason to believe this step-by-step process is for real.

And the multiple sensors add an array of possibilities. In a few months, the company says it will add a fifth kind of headband practice: walking meditation. For this one, unlike the others, it is recommended that you keep your eyes open.

Heart of the matter

For all of the new meditations, the Muse app uses the same scoring system as it employed in its regular brain-sensing meditation.

You get three scores at the end of each session: a number of birds (you hear birds when the Muse registers a low level of brain activity relative to the baseline established in the calibration), a number of "recoveries" (moments when you were able to swiftly bring your brain, breath or heart rate back in the right direction), and "muse points" based on how well you did overall.

But the sounds you'll hear in every kind of meditation are now wildly different. For the regular brain-based version, you'll still hear birds when you're calm and a nature sound of your choice when you aren't (a rainstorm, the ocean, the desert wind, ambient music — or city noises, which effectively constitutes a difficult "boss level").

The other meditations don't appear to feature birds, even though you get a bird score at the end. In the heart rate meditation, your quickening or slowing pulse is represented by the sound of a drum. The breathing meditation gives you a voice telling you when to breathe in and out, along with ambient noise on the inhale and a pleasant whooshing sound on the exhale.

And the stillness meditation gives you wind chimes if you move, which seems reason enough to stay still.

As in all meditation apps, there's perhaps just a touch too much New Age-yness that might turn off the beginner. By default, the Muse app includes a guided meditation introduction with an overly slow, calm voice that repeats itself a fair amount. Maybe after a few more years of practice I'll be zen enough to accept this, but for now I prefer to turn off the voice and cut to the chase.

Still, InteraXon has done everything it can to make the learning curve a steep one. Friendly animated videos play before you try any given meditation for the first time. There's a helpful on-screen guide on what to do if your headband isn't working; cinching it tighter, cleaning your forehead or adding a drop of water to the electrodes are the most likely solutions.

Is all of this worth $250 (which happens to be $50 less than the original Muse sold for in 2014)? Your mileage may vary, but to my mind (no pun intended) it absolutely is. Both Headspace and Calm offer lifetime subscriptions for $299, and they don't give you useable data on your meditation practice.

Use the Muse every weekday for a year, and you've spent a dollar per day -- not a high price to pay for more peace of mind.

InteraXon also has a body of science to back up its claims about the Muse's effectiveness. The company can boast hundreds of third-party research papers that use the Muse as a tool, including a study from the University of Milan that showed four weeks of Muse usage lead to improved cognitive performance.

A better, calmer, less distracted brain? That's not something any of the other devices in my must-carry list can offer -- and it's why the Muse 2 is likely to remain one of my most essential gadgets for at least another four years.