Garmin Smart Watch

Biohacker Review: The lowest-friction health optimization device I’ve strapped on

I’ve been self-quantifying my health for over a decade now, long before it was fashionable or packaged into slick consumer dashboards. My first serious foray into HRV tracking started more than ten years ago with HeartMath devices. Back then, tracking heart rate variability felt almost monastic. You had to carve out time, sit down, attach sensors, and do the thing. It worked, but it required discipline, ritual, and bandwidth. As life has grown fuller, busier, and more complex, that kind of friction has become increasingly expensive.

At this stage of life, as an entrepreneur, a husband, and now a new father, what I value (especially when it comes to Biohacking tech) is low-friction leverage. And I think I’ve finally found it.

The Garmin vívosmart® 5 has become, for me, the lowest-friction self-quantification and health optimization device I’ve ever used.

About Garmin's HRV-Tracking Smart Watches

I interviewed one of the top doctors in Norway about heart rate variability, and he convinced me that Garmin's Smart Watches are the best wearable HRV/fitness trackers. They give you a real-time body battery, sleep scores, and a wealth of other data.

Having done over 300 HRV training sessions with HeartMath's devices clipped to my ear, I really liked the idea of an HRV tracking watch. The issue with many HRV devices is that you only give biofeedback data when you're using them. Whereas, a watch is just a watch - you can sleep, swim, eat, or even make love with it on (just be careful with the lube!) Garmin's watches with the full suite of health tracking features start at $150.

So Christmas of 2024, I bought my wife a Garmin Lily® 2--she loves it. It’s an elegant watch that actually looks good on a woman’s wrist, which is no small feat in the wearables world. She wore it throughout her pregnancy, used some of the pregnancy-related apps, and I genuinely believe it helped her manage stress and listen to her body more intelligently during that period. Fast forward to Christmas 2025, and she returned the favor by getting me a Garmin smartwatch.

Sleep scores: Not accurate

My wife and I have both learned to disregard the sleep scores somewhat. We've both grown to suspect that it presents an overly pessimistic picture of our sleep and state of energy. 

Today was a good example of this: I got 7 hours of sleep, a 47 sleep score, and woke up with a body battery of 23--those are pretty bad scores. And it was a mediocre night of sleep. I had a glass of wine, and then the Balkan summer heat woke me up 2-3 times during the night. But really, I feel quite alright today. I got everything done; good focus, productivity, and creativity. 

The next day, I was determined to do better. So I did everything right: I abstained from a glass of wine, ate a light dinner early, avoided screens before bed, and made love to my wife before falling asleep. The result: 48 sleep score/28 body battery. 

I've also experienced the inverse a few times. I've had unproductive days with mediocre energy when my body battery and sleep scores were good. And a few weekends ago, I got a great sleep score even after indulging in a delicious, tall, craft European beer. 

So Garmin's got me asking, "What's the point of all my sleep hygiene practices? Why NOT have a second glass of wine and stay up another hour watching a movie with my wife?"

Oddly enough, anytime I didn't sleep with my Garmin watch on (because it needed to be charged overnight), I'd notice that my body battery was consistently a bit higher than if I wore it while sleeping. Which, of course, prompts the question: is the watch "lying" to me about Body Battery in its good morning wake-up report, or upon strapping it back on? I'm not the only person to notice that Garmin's sleep scores are more than a bit slippery; The Quantified Scientist did a scientific breakdown here...

More and more, I'm returning to three heuristics that I used to judge my sleep quality

1. Starting work in the morning, do I make a lot of mistakes typing? (Of course, I have a bunch of AI voice dictation and spellchecking apps I use, but typing accuracy is a pretty good gauge for me on my brainpower)
2. In the morning, do I have the body energy to use my standing desk? Or do I really feel like sitting?
3. Are my energy levels crashing by mid-afternoon? Do I have the brainpower left to do a call with a client or a podcast interview at 5:00 PM?

A horrifying confirmation about my sleep

Within days of wearing the vívosmart® 5, I had what I can only describe as a mildly horrifying confirmation. My sleep quality was mediocre.

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Not catastrophically bad. Not “you need a sleep lab” bad. But mediocre in a way that’s insidious. The kind of sleep that lets you function while quietly robbing you of energy, mood, and long-term resilience. And of course, sleep is the master lever. Everything else in health, cognition, emotional regulation, and performance sits downstream from it. The data gave me just enough discomfort to start experimenting.

Two things became immediately obvious:

• First, my nightly habit of enjoying one or two glasses of dry Bulgarian red wine with dinner was absolutely hitting my sleep quality. The HRV and sleep scores didn’t moralize. They didn’t shame. They simply showed me the tradeoff, night after night.
• Second, temperature mattered more than I had been giving it credit for. Here in Eastern Europe, keeping the bedroom cooler often just means not running the space heater at night. That small change alone noticeably improved my sleep scores.

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Over time, by making small, rational adjustments, my sleep scores climbed into the 80–90 range consistently. That’s solid territory.

Body Battery ≠ brainpower?

Interestingly, there's not a great correlation between Body Battery and my cognitive performance in my Dual N-back brain training - but there does seem to be with my sleep scores.

Dual N-Back	Body Battery	Sleep Score

I guess there's a reason they call it Body Battery and NOT Brain Battery.

Why I chose the most minimal Garmin

I intentionally chose the vívosmart® 5 because it’s one of Garmin’s most minimal offerings and also one of the most affordable. Importantly, “minimal” here does not mean lacking health data. It tracks HRV, sleep, stress, body battery, and the metrics that actually matter, without trying to become a second smartphone on your wrist.

I’m a watch guy. I appreciate analog aesthetics. On my right wrist, I usually wear a beautiful Bulova that was gifted to me years ago by a financier who was, quite literally, clinically insane (but that’s a story for another time). Sometimes I switch it up with a sleek black Guess watch.

The Garmin lives on my left wrist - quiet, functional, comfortable - not messing with my timepiece game.

Enabling an underrated lifehack: Less Sleep, Higher Quality

Here’s the unexpected upside I didn’t anticipate. By tracking sleep quality instead of obsessing over sleep quantity, I’ve managed to increase the quality of my sleep while decreasing the total hours.

The mainstream advice still parrots “eight hours no matter what,” but newer research suggests that around seven hours is optimal for many people. For a busy entrepreneur and parent, that reclaimed hour in the morning is enormous.

Now, when I wake up early, I don’t guess. I don’t negotiate with myself. I check my Body Battery (takes just two or three taps on the watch's touchscreen).

• If it’s above 70, I consider that a restorative night. I get up and start the day.
• If it’s below 70, I try to go back to sleep.

Final Verdict

The Garmin vívosmart® 5 has earned a permanent place in my life because it does something rare in Biohacking: It improves outcomes without demanding attention.

No rituals. No constant fiddling. No obsession. Just quiet, continuous feedback that nudges behavior in better directions. For where I’m at in life, that’s exactly what I want.

I’ll continue to report back as I gather more long-term data, but for now, this is the most practical, low-friction health optimization device I’ve found.