Smartwatches are often marketed as tools that can help monitor your well-being throughout the workday, ensuring that daily life doesn't become overwhelming. However, a recent study has concluded that these devices may not accurately measure your stress levels as intended. In fact, the study indicates that smartwatches may mistake feelings of excitement for overwork, leading to misleading stress readings.
Researchers discovered a minimal correlation between the stress levels reported by smartwatches and the levels participants reported experiencing. While there was a slight association between recorded fatigue and smartwatch data, sleep metrics showed a stronger correlation. Eiko Fried, one of the study's authors and an associate professor in the department of clinical psychology at Leiden University in the Netherlands, remarked that the correlation between smartwatch readings and self-reported stress was "basically zero."
Fried elaborated, stating that heart rate—one of the primary metrics monitored by smartwatches—does not accurately reflect emotional states. He shared personal anecdotes, noting how his Garmin smartwatch inaccurately flagged him as stressed during workouts and excited conversations at social events. This highlights a significant concern regarding the reliability of wearable technology in assessing mental health.
The findings raise critical questions about the capabilities of wearable data in understanding mental states. Fried cautions users, urging them not to rely solely on their smartwatches for emotional insights. "These are consumer devices, not medical devices," he emphasized. Although there is ongoing academic research aimed at finding physiological indicators of emotional states, many of these studies lack precision due to the overlapping nature of positive and negative feelings.
Fried and his research team monitored stress, fatigue, and sleep over three months, involving 800 young adults who wore Garmin Vivosmart 4 watches. Participants were asked to report their feelings of stress, fatigue, and sleepiness four times a day. The results, published in the Journal of Psychopathology and Clinical Science, revealed that none of the participants' smartwatch stress scores met the baseline for significant change, even when they self-reported feeling stressed. Furthermore, a quarter of the participants experienced discrepancies between their smartwatch readings and personal feelings.
Fried noted that the relationship between smartwatch data and physical fatigue—referred to by Garmin as "body battery"—was somewhat stronger than that for stress, yet still weak overall. While Garmin does not disclose the formula for calculating the body battery score, Fried suspects it combines pulse measurements with activity levels.
When examining sleep data, the correlation was even stronger, with two-thirds of participants showing significant associations between their smartwatch readings and self-reported sleep quality. The researchers found that a transition from a day of poor sleep to a day of good sleep could predict an increase in sleep duration measured by the smartwatch of approximately two hours. "This is a really noticeable effect," the researchers stated.
This research aims to contribute to an early warning system for depression, potentially allowing wearable tech users to receive data that may prompt preventive treatments before depressive episodes occur. While there are promising indicators that lower activity levels could signal worsening mental health, Fried is still investigating whether this is due to exercise's protective effects or a decline in energy levels as mental health deteriorates.
Margarita Panayiotou, a researcher at the University of Manchester, commented on the study, stating, "Wearable data can offer valuable insights into people’s emotions and experiences, but it’s crucial to understand its potential and limitations." She emphasized that the research clarifies what wearable data can reliably convey, contributing significantly to ongoing discussions about technology's role in understanding well-being. It's vital to remember that wearable data does not necessarily reflect objective reality and should be interpreted alongside individual perceptions and lived experiences.
As the conversation around mental health and technology continues to evolve, it remains essential to approach smartwatch data with caution and awareness of its limitations. Garmin has been approached for comment regarding the implications of these findings.
