Smartwatches are intended to track your well-being throughout the workday, ensuring your life remains balanced.

However, recent studies indicate that these devices are not reliable for accurately assessing stress levels. You may feel overwhelmed when you’re actually just excited.

The findings showed only a weak correlation between smartwatch-reported stress and the levels participants claimed to have felt. In contrast, fatigue was somewhat related to the smartwatch data, while sleep metrics had a stronger association.

Eiko Freed, the study’s author, stated that the connection between smartwatch stress readings and self-reported stress was “essentially zero.”

He further explained, “It’s not surprising since the device doesn’t accurately reflect your emotions and may even heighten feelings of excitement and pleasure.”

Freed recalled that his Garmin had flagged him as stressed while he was exercising and enthusiastically chatting with a long-lost friend from his wedding.

“These findings prompt critical considerations about the ability of wearable tech to truly reflect our mental states,” Fried remarked. “Exercise caution; don’t rely solely on smartwatches. They are consumer gadgets, not medical instruments.”

Freed noted that while many researchers are exploring physiological indicators that could represent emotional states, the accuracy is often insufficient due to the overlap of positive and negative emotions. For instance, increased heart rate can indicate both anxiety and excitement.

Fried, an associate professor at Leiden University’s Clinical Psychology Department, monitored stress, fatigue, and sleep over three months in 800 young adults using Garmin Vivosmart 4 watches. Participants were asked to report their feelings about stress, fatigue, and sleepiness four times daily, which were then compared to the smartwatch data.

As published in the Journal of Psychopathology and Clinical Science, none of the participants found that their smartwatch stress readings accurately reflected their self-reported stress levels. For 25% of participants, the smartwatch indicated they were either not stressed or stressed when they felt quite the opposite.

The link between physical fatigue, dubbed “body battery” by Garmin, was “significantly stronger than stress but overall still weak,” Fried mentioned. Garmin attributes this to a combination of pulse rates and activity levels, though they do not disclose the specifics of how the body battery score is calculated.

The connection to sleep proved to be stronger, although Freed acknowledged the need for improved measurements on undisturbed rest.

In about two-thirds of sleep assessments, a notable correlation between Garmin readings and self-reported data was observed. Researchers highlighted that participants often projected that Garmin sleep duration would increase by around two hours if they reported improved sleep quality compared to a prior day rated poorly. “This effect is quite remarkable,” they noted.

The study aspires to establish early warning systems for depression, enabling wearable technology users to receive data that may facilitate preventive care before a depressive episode occurs.

There are initial indicators suggesting that reduced activity levels could be predictive, although Fried has not yet determined whether this stems from exercise’s protective role against depression or if declining energy arises as mental health deteriorates.

“Wearable technology can offer insightful information about emotions and experiences, but it’s vital to understand their limitations,” stated Margarita Panayiotou, a researcher at the University of Manchester.

“This study will elucidate the reliable insights such data can provide and contribute significantly to the ongoing discussion regarding technology’s role in understanding happiness. It’s crucial to remember that wearable data might not represent objective truths and should be interpreted within a broader context, including individual experiences and perceptions.”

Garmin was contacted for comments.