Garmin Is BAD At Sleep Tracking. And That's Okay!
In a Nutshell
Garmin watches consistently rank among the worst for sleep stage tracking across three independent evidence sources: a University of Salzburg study against polysomnography, personal EEG testing, and a meta-analysis of scientific literature. While Garmin's heart rate measurements during sleep are reliable and correlate well with reference devices, sleep stage accuracy for deep sleep, REM, and awake time is notably poor compared to competitors like Aura Ring, Whoop, Pixel Watch, and Apple Watch. This stems from Garmin's design priority on sports tracking features rather than sleep analysis, making their watches suitable for users who value GPS, battery life, and ecosystem connectivity over precise sleep staging.
These notes were generated by AI and may contain inaccuracies.
Your Garmin watch is likely quite bad at sleep stage tracking compared to the competition. The speaker will show three lines of scientific evidence for this, but will also demonstrate what Garmin watches are good at during the night and why this might not be a major issue for some users.
Sleep tracking performance is usually the same across Garmin devices. Every Garmin device will perform more or less the same for sleep stage tracking, whether it's a Fenix device, Garmin X1, or Venue series.
A sleep study conducted with the University of Salzburg involved 18 people over approximately four to five nights wearing different wearables. The devices tested included Garmin (plotted in red), Polar, Aura, Whoop, Apple, Google, and the Circle Plus ring (plotted in black).
The wearables were tested by comparing them against polysomnography, the gold standard sleep stage tracking. This involves electrodes measuring heart rate, eye movements, and brain waves to get the most reliable measurements of sleep stages.
Performance was compared using Cohen's Kappa (horizontal axis, higher is better) and sensitivity (vertical axis). The analysis took the average value per person, with each dot representing one person for one wearable across all nights. The average performance of all devices was subtracted for each person, meaning devices to the left of zero performed worse than average, and those to the right performed better than average.
Garmin devices (shown in red) were almost always below zero, performing worse than the average device. Only in one case was Garmin slightly better than average. Polar's Sleep 2 algorithm and Aura performed best, followed by Apple, then the old Google algorithm.
When devices were ranked per person (best to worst), the Sleep 2 algorithm performed best but had an unfair advantage since it was tested in the same lab where it was developed. Ignoring Sleep 2, the best device for most people was either an Apple Watch or Aura ring. The second best was often an Apple Watch, ring, or sometimes Whoop strap or Pixel Watch.
Garmin was almost always the second worst device, typically in sixth position. Only the Circle Plus ring performed worse. Out of all commonly used devices tested, Garmin performed the worst.
Ranking based on average sensitivity produced very similar results, with Garmin almost always the second worst device. Better performance was consistently achieved with Aura Ring or Whoop strap.
The study concluded that sleep stages (deep sleep, light sleep, REM sleep, and awake time) weren't reliable on Garmin compared to the competition. Both good and bad nights of sleep were included, and the consistency across 17-18 participants suggests Garmin likely isn't the best sleep stage tracker.
Personal testing was conducted using different Garmin watches, calculating average sensitivity and worst sensitivity across all sleep stages (deep sleep, light sleep, and REM sleep). This NF1 test was conducted against EEG, an imperfect reference that still measures eye movements and brain waves but isn't as complete as polysomnography.
Apple Watch, Whoop Strap, Aura Ring, and Pixel Watch all performed better than various Garmin devices tested, including Garmin Forerunner 570, Venue 4, Instinct 3, Vivo Active 6, and others. All Garmin devices performed worse.
2024 testing showed similar results with Garmin devices performing worse than Aura Ring, Pixel Watch, and HL Pod. Polar appeared quite low because this was the internal algorithm, not Sleep 2.
The best devices identified were Pixel Watch, Galaxy Watch (improving but not quite there yet), Whoop Strap, Aura Ring, and HL Pod. The HL Pod is expensive but is the speaker's favorite sleep improvement device because it can actively cool and heat each side of the bed independently.
A meta-analysis was conducted of all available literature, creating an overview where devices further to the top right show better agreement with the reference. Garmin was found at the bottom, with most devices performing better. Sleep 2, Aura Ring, Google, and Whoop Strap all performed better than Garmin.
The three lines of evidence (Salzburg study, personal testing, and meta-analysis) all showed consistent results. If someone is particularly interested in sleep stages (deep sleep, awake time), Garmin cannot be recommended as the best sleep stage tracker.
This performance gap is likely because sleep tracking is not Garmin's focus. Garmin is a sports watch that prioritizes long battery life, great GPS, and broad ecosystem connectivity (chest straps, indoor bikes, etc.). These are the things Garmin does well.
Looking at individual sleep stages, Garmin performed very poorly for awake time and REM sleep. Light sleep was okayish compared to competition but still not great. Deep sleep wasn't quite as bad but some devices performed significantly better.
Garmin performs well at heart rate measurements during the night. When compared to the Aura Ring across 20-30 nights, there was a nice correlation between the two, though Garmin tended to detect slightly higher heart rates. The general patterns matched very well across individual nights.
For lowest heart rate measurements, Garmin performed really well with the same resting heart rate values as Aura Ring, aside from three outliers where the battery may have died.
Garmin consistently detected slightly higher average heart rate compared to Aura Ring, but maintained a super high correlation. The patterns between nights remained more or less identical, meaning if Garmin showed a five-point higher heart rate one night compared to the previous night, it would align with other devices.
Heart rate measurements from Garmin devices are trustworthy and may be more important to users than deep sleep amounts. This aligns with Garmin's primary focus as sports trackers rather than sleep trackers first.
Garmin has been using more or less the same sleep stage tracking for many years and has fallen behind the competition. The sleep stages won't be as reliable as other brands, though not everybody uses sleep stages - it might be considered a nice-to-have feature.
Reference measurements of sleep stages aren't perfect. When two independent labs measure light sleep, deep sleep, REM sleep, and awake time, they typically achieve high 80s or 90% agreement. This is considered more than good enough to judge which devices are good or bad.
The imperfect nature of reference devices shouldn't be used as a reason not to judge devices as better or worse, as the differences observed were too significant. Any reference device or testing (in scientific papers or YouTube videos) will be imperfect, but even imperfect information contains valuable evidence.
If choosing a Garmin watch (X1, Fenix, Venue, Forerunner), be aware that sleep stages won't be as reliable. Alternative recommendations include Whoop Strap (favorite for health and sports tracking combined), Aura Ring (favorite for health tracking), or Eight Sleep Pod for sleep improvement.
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