Apple Watch vs Garmin: quale monitora meglio il sonno?

Day 70: Apple Watch vs Garmin — Which One Actually Tracks Sleep Better?

I had no idea how to compare sleep tracking properly, so I looked for actual research. Turns out scientists have done exactly this — comparing both Garmin and Apple Watch against polysomnography, the gold-standard sleep test done in a clinical lab with sensors attached to your head and body.

Here's what the science says — and why the lab result doesn't tell the whole story.

Both are good at detecting when you're asleep

For the most basic task — detecting when you fall asleep and when you wake up — both platforms perform well. Sensitivity rates for correctly identifying sleep time are typically above 90% for both Garmin and Apple Watch when compared against polysomnography. The total sleep time you see in the app is reasonably accurate on both sides.

Apple Watch is slightly better at detecting sleep stages

Where Apple pulls ahead is in sleep stage classification — detecting whether you're in light sleep, deep (slow-wave) sleep, or REM sleep.

Studies published in journals like Sleep Medicine and npj Digital Medicine consistently show that Apple's algorithms — which combine accelerometer movement data with heart rate and heart rate variability — outperform most Garmin models at detecting REM and deep sleep. Apple has invested heavily in training these models with large clinical datasets.

Garmin has improved considerably. Newer models like the Fenix 8, Forerunner 965, and Epix Pro now include continuous Pulse Ox monitoring and advanced HRV sensing during sleep. But Apple's sleep stage accuracy still holds a measurable lead in controlled studies.

But who actually wears their watch to bed?

Here's where the comparison gets practical — and where Garmin wins the real-world argument.

The Apple Watch lasts roughly 18 hours on a full charge. Most Apple Watch users charge it overnight. That means the sophisticated sleep tracking almost never gets used consistently.

Garmin watches tell a completely different story:

• Forerunner 165: up to 11 days battery life
• Forerunner 965: up to 31 days in smartwatch mode
• Fenix 8: up to 29 days
• Epix Pro: up to 31 days

Because Garmin users almost never charge overnight, sleep tracking is actually used — consistently, night after night. That continuous data builds a reliable personal baseline, tracks trends over weeks and months, and becomes genuinely useful over time. Garmin's HRV Status, Body Battery recovery scores, and sleep quality trends only improve with more nights of data behind them.

An Apple Watch with better algorithms but missing data is less useful than a Garmin with slightly less accurate algorithms but a complete sleep history going back a year.

The verdict

Apple Watch may score higher in a controlled lab comparison. Garmin wins in the real world — because people actually wear it to bed, charge it on a run, and never miss a night of tracking.

If you're choosing a watch specifically for sleep tracking, battery life should be near the top of your list. A slightly less accurate sleep stage reading that runs every single night is far more valuable than a highly accurate one you never capture because the watch was on the charger.