A Sweat-Based Sensor May Help Improve Sleep Quality Through Continuous Hormone Monitoring

Researchers at the University of Texas at Dallas (UT Dallas), working in collaboration with Texas-based biotech company EnLiSense, have developed a wearable sweat-based sensor that could change how sleep quality and circadian health are monitored. The technology focuses on continuously measuring two critical hormones—cortisol and melatonin—that play central roles in regulating the body’s sleep–wake cycle.

The study presents a new, non-invasive way to track these hormones using passive perspiration, meaning sweat naturally produced by the body without any stimulation. The findings were published as a proof-of-validation study in the scientific journal Biosensors and Bioelectronics: X, marking an important step forward in wearable health technology.

Why Cortisol and Melatonin Matter for Sleep

Sleep quality is closely tied to the body’s internal clock, also known as the circadian rhythm. Two hormones are especially important in this process. Cortisol is often referred to as a stress hormone, but it also promotes alertness and wakefulness, typically peaking in the morning. Melatonin, on the other hand, signals the body that it is time to sleep and usually rises in the evening and overnight.

Accurately tracking the fluctuations of these hormones over a full day is essential for understanding sleep patterns, stress levels, and overall circadian health. However, current clinical methods make this difficult outside of controlled laboratory environments.

Limitations of Current Hormone Monitoring Methods

At present, saliva sampling is considered the gold standard for measuring cortisol and melatonin. While effective, it comes with significant drawbacks. In sleep studies, participants often have to be awakened multiple times during the night so technicians can collect samples. This process is inconvenient, disruptive to sleep, and impractical for long-term or everyday monitoring.

Because of these challenges, there has been growing interest in developing non-invasive, continuous monitoring tools that can work in real-world conditions without interfering with normal sleep.

How the Sweat-Based Sensor Works

The newly developed sensor uses electrochemical sensing technology to continuously measure cortisol and melatonin levels in sweat. The device is built on EnLiSense’s CORTI wearable platform, which is designed to be worn comfortably over extended periods.

What makes this approach unique is its use of passive sweat. Unlike some wearable biosensors that require heat, exercise, or electrical stimulation to induce sweating, this device relies solely on sweat that the body naturally produces throughout the day and night. This allows for uninterrupted monitoring, including during sleep.

According to the researchers, this is the first study to demonstrate circadian rhythmicity of both cortisol and melatonin measured through sweat, rather than saliva or blood.

Details of the Validation Study

The study involved 43 participants, each of whom wore the sweat-based sensor continuously for 48 hours. During this period, researchers also collected 12 saliva samples per participant. These samples were used as a reference to compare hormone levels measured by the wearable sensor.

The results showed that hormone readings from the sweat-based sensor closely matched those obtained from saliva samples. This strong agreement confirmed the accuracy and reliability of the wearable device. The ability to capture consistent daily patterns of cortisol and melatonin through sweat validated the sensor as a credible alternative to traditional methods.

Contributions from the Research Team

A key contributor to the study was Annapoorna Ramasubramanya, a doctoral student in biomedical engineering at UT Dallas and the study’s first author. Her role focused on translating raw sensor data into meaningful thresholds that could be applied to stress monitoring, wellness tracking, and circadian rhythm analysis.

Her work helped bridge the gap between chemical measurements and practical health insights, making the data easier to interpret for future clinical and consumer applications. In recognition of her contributions, Ramasubramanya received a New Investigator Award at the World Sleep Congress 2025 in Singapore, an event organized by the World Sleep Society.

The study was led by Dr. Shalini Prasad, professor and department head of bioengineering at UT Dallas and the corresponding author of the research. She is also a co-founder of EnLiSense and has spent years developing wearable biosensor technologies.

The Role of EnLiSense and Commercialization

EnLiSense is actively commercializing the CORTI sensor platform, building on more than a decade of research in wearable biosensing. The company specializes in passive sweat sensors and aims to bring laboratory-grade biochemical monitoring into everyday life.

The CORTI device is positioned as a tool that could provide objective hormone data, something current consumer sleep trackers do not offer. Most commercially available wearables estimate sleep quality based on indirect signals such as movement, heart rate, and sometimes skin temperature. While useful, these metrics do not directly measure the biological processes that regulate sleep.

Why This Technology Could Be a Game Changer

By directly measuring cortisol and melatonin, the sweat-based sensor offers a more biologically grounded view of sleep health. This could be especially useful for people experiencing circadian rhythm disruptions due to stress, irregular schedules, extensive screen use, or lifestyle factors that affect sleep timing and quality.

Researchers also note broader implications for mental health, as sleep quality is closely linked to conditions such as anxiety, depression, and chronic stress. Continuous hormone monitoring could help identify patterns that are difficult to detect with traditional sleep tracking tools.

Broader Context: Circadian Health and Modern Life

Circadian rhythms can be disrupted even without extreme conditions like shift work or frequent travel. Exposure to artificial light, constant digital connectivity, and irregular sleep schedules can all interfere with natural hormone cycles. Technologies that provide clear, objective insights into these disruptions could help individuals and clinicians make more informed decisions about sleep habits and interventions.

The study also contributes to the field of chronobiology, which focuses on understanding natural biological rhythms. By offering continuous data rather than isolated measurements, the sensor opens new possibilities for research and personalized health monitoring.

Looking Ahead

While further studies and regulatory steps will be needed before widespread adoption, this research demonstrates that sweat-based hormone monitoring is both feasible and accurate. It represents a meaningful advance toward wearable devices that do more than estimate sleep—they directly measure the hormones that control it.

As interest in sleep health continues to grow, technologies like this could play a key role in shaping the next generation of health wearables.

Research paper:
https://doi.org/10.1016/j.biosx.2025.100656