In recent years, wearables have evolved far beyond simple fitness trackers. Devices like smartwatches now offer ECG readings, stress monitoring, and even sleep apnea detection. But what if they could also track something even more personal—our emotions?

Researchers at Tokyo Metropolitan University have taken a major step toward making this a reality. A team, led by Professor Shogo Okamoto, has conducted (PDF version) studies that suggest it’s possible to measure emotional responses by monitoring changes in skin conductance—essentially how our skin’s electrical properties change when we experience various emotions. The team tested this by showing volunteers videos designed to trigger specific emotional reactions, such as fear, family bonding, or humor, and measured their skin’s response.

The skin’s conductance varies with emotional stimuli because emotions trigger the sweat glands, a response controlled by the sympathetic nervous system. These changes in sweat levels can be detected through sensors on the skin, giving insight into how strongly we are feeling something within seconds. The Tokyo team found that fear produced the longest response, which aligns with evolutionary traits tied to danger detection. Meanwhile, emotions tied to family bonds were slower to develop, likely due to the mixed nature of joy and sadness that such moments can evoke.

The potential of this research isn’t just academic. Wearable devices like Fitbit’s Sense and Charge 6 already include electrodermal activity (EDA) sensors that detect changes in skin conductance to monitor stress levels. These devices are already used for stress management, but they could soon be adapted to give deeper insights into emotional states, from anxiety to joy or sadness. The hope is that, in the future, wearables could not only track your physical health but also provide real-time emotional insights, guiding users through moments of emotional distress.

While we’re still far from fully understanding the full spectrum of human emotions, the Tokyo Metropolitan University team is optimistic that this technology, combined with other biological signals, could lead to smarter devices that understand how we feel. As companies like Apple, Google, and Samsung continue to explore emotional analysis, it’s clear that this could be the next frontier in wearable tech—opening up new possibilities for personalized health and well-being.