Your smartwatch confidently declares you’re “highly stressed” while you’re laughing at TikTok videos on the couch. Meanwhile, during actual deadline panic, it cheerfully reports you’re “relaxed.” Turns out there’s science behind why these devices are about as reliable as a Magic 8-Ball for measuring psychological stress.
The Research That Burst the Bubble
A Dutch study of 800 users reveals the uncomfortable truth about wearable stress tracking
A massive Dutch study tracked nearly 800 young adults wearing Garmin Vivosmart 4 devices for three months, comparing the watches’ stress readings against what people actually reported feeling four times daily via smartphone check-ins. Published in the Journal of Psychopathology and Clinical Science, the results were brutally clear: “very weak to no associations” between device metrics and self-reported stress levels.
The participants weren’t just casual users either—they committed to ecological momentary assessment (repeated self-reports throughout the day), the gold standard for capturing real-time psychological states. When smartwatches screamed stress alerts, users rarely reported feeling stressed. The correlation was so weak researchers essentially found no meaningful relationship.
Key findings from the study:
- Smartwatch stress alerts showed minimal overlap with users’ actual reported stress
- Sleep duration tracking performed better than stress measurement, though sleep quality readings remained unreliable
- Heart rate variability calculations get confused by physical activity, excitement, and even sexual arousal
- The 0-100 stress scores rely on questionable assumptions about what elevated heart rate actually means
Expert Reality Check
Researchers warn against treating consumer devices like medical instruments
Study co-author Eiko Fried delivered the kind of blunt assessment that smartwatch marketing teams probably hate: consumers should not “live by your smartwatch” because these are consumer devices, not medical instruments. Heart rate spikes during excitement, arousal, or even anticipation of your favorite song—not just anxiety or psychological stress.
This isn’t about attacking useful technology. Garmin’s Vivosmart 4 analyzes heart rate variability while you’re inactive and outputs readings using established algorithms. The problem lies in interpretation. Your device can’t distinguish between the physiological signature of deadline stress and the rush of spotting your crush across a crowded room.
What This Actually Means for You
Practical guidance for smartwatch owners who’ve been relying on stress scores
Stop treating stress scores like medical diagnoses. These devices excel at tracking concrete behaviors—sleep duration, step counts, heart rate during exercise—but struggle with psychological state inference. Your smartwatch is essentially making educated guesses about complex mental states using limited physiological data.
The research suggests focusing on trends rather than individual readings, and never using stress scores to make important decisions about your mental health. If you’re genuinely concerned about stress levels, those feelings matter more than whatever your wrist computer thinks about your heart rate variability.