Wearable validation study targets nocturnal scratching in pruritic skin disease
Nocturnal scratching has long been one of the most difficult symptoms in atopic dermatitis and other pruritic disorders to measure with any consistency. Patients can describe the burden, but the signal itself is brief, repetitive, and easy to miss unless someone watches through the night. Replior AB is now running an observational analytical validation study of its ScratchSense ring to test whether a wearable sensor can identify and quantify scratching during sleep with enough reliability to support research use.
The study is being conducted in adults with itch-related conditions, including atopic dermatitis, chronic pruritus of unknown origin, and other pruritic dermatological or systemic diseases. Enrollment is estimated at 35 participants, with an age range of 18 to 65 years. The protocol requires evidence of nocturnal itching and scratching, either documented or self-reported, and participants must have experienced nocturnal scratching within the prior seven days and be considered likely to scratch during the study period.
A single-sensor strategy is not the point here. Investigators are asking a more basic question: can motion and contact-vibration signals captured from two finger-worn devices distinguish scratching from ordinary sleep movement well enough to build a dependable digital biomarker?
Why nocturnal scratching is so hard to capture
Scratching during sleep sits at the intersection of dermatology, sleep medicine, and sensor engineering. It can reflect ongoing inflammatory disease activity, but it also disrupts sleep architecture and worsens quality of life in ways that are hard to quantify from recall alone. Self-reports can be incomplete, sleep diaries depend on memory, and video monitoring is labor-intensive. Even when video is available, interpreting brief hand movements frame by frame is not a scalable solution for routine clinical research.
The planned answer in this study is a controlled environment with layered measurement. Participants will wear two Replior ScratchSense rings, one on each hand, placed on the index or middle finger. They will also undergo overnight thermal camera video recording and wear a polysomnography system during sleep for three nights. The ring is designed to detect nocturnal scratching through motion and contact-vibration signals while also collecting sleep-related movement patterns and measures of scratch-related intensity and pressure.
That combination matters because scratching is not simply movement. It is a patterned mechanical event, and the ability to capture both motion and contact vibration may help distinguish it from unrelated nocturnal hand activity. In a condition like atopic dermatitis, where itch intensity can fluctuate from night to night, a device that can track repeated scratch bouts in real time could eventually give researchers a more objective way to connect symptom burden with disease control.
The validation question centers on scratch bout detection
The primary outcome is the number of scratch bouts, defined as a group of one or more scratch events occurring in close temporal proximity. The time frame runs from enrollment to Night 3, which is Visit 3. The study’s secondary outcome is Total Sleep Time, measured as the total minutes actually spent asleep across the night from enrollment to Night 3.
This is an analytical validation study rather than a therapeutic trial. No treatment effect is being tested, and no clinical intervention is being compared against another. The purpose is narrower but essential: assess the ring’s accuracy, precision, specificity, and overall reliability in a controlled setting. For a device intended to quantify nocturnal scratching, those operating characteristics are the difference between a promising prototype and a usable research tool.
The study design is prospective and observational, with an “other” observational model. Participants must also be willing to complete questionnaires and attend study visits. Written informed consent is required before selection, including specific consent for thermal video recording. The site listed in the record is Grenoble, France, at Eurofins Optimed, and the study is recruiting.
Eligibility rules reflect the biology of scratching and the limits of motion sensing
The exclusion criteria show how carefully the protocol tries to preserve signal quality. Participants are excluded if they have no current or expected nocturnal itch, including well-controlled conditions or no recent reports of nighttime scratching. The study also excludes confounding movement disorders or sleep conditions such as restless legs syndrome, periodic limb movement disorder, moderate or severe obstructive sleep apnea, Parkinson’s disease, or other conditions that could interfere with motion analysis.
Recent changes in anti-pruritic treatment are another major filter. The protocol excludes initiation or dose changes of systemic medications that may suppress nocturnal itch within the past two weeks, including oral corticosteroids, immunosuppressive agents such as cyclosporine or methotrexate, and biologics such as dupilumab unless the participant has been on a stable dose for at least eight weeks. Sedating antihistamines are excluded unless stable for at least one week. Topical corticosteroids, calcineurin inhibitors, or emollients initiated within three days before study start are also excluded, and there can be no use during the study.
These restrictions are clinically sensible. A wearable designed to detect scratching cannot be judged fairly if the underlying itch is changing because of new treatment, or if another sleep disorder is producing hand and limb movements that mimic scratching. The protocol is trying to isolate the scratch signal from everything that could dilute it.
A small study, but a meaningful technical hurdle
The estimated enrollment is only 35 participants, which is consistent with a device validation exercise rather than a large clinical outcomes study. The objective is not to prove that scratching causes worse sleep, or that the ring improves care. Instead, the study is trying to establish whether a finger-worn sensor can continuously and non-invasively measure a symptom that has resisted objective tracking for years.
If the device performs well, the implications would be methodological first. Researchers studying atopic dermatitis, chronic pruritus, and other itch-driven disorders would gain a way to quantify nocturnal scratching without relying entirely on patient recall or a bedside observer. Sleep time data may also help contextualize scratch burden, since the total minutes actually spent asleep can influence how much opportunity exists for scratching to occur.
The record provides no results yet, and no performance data are posted. What is concrete now is the design itself: an observational, prospective validation study using dual finger sensors, thermal overnight recording, and polysomnography to test whether ScratchSense can distinguish a clinically important symptom from the background noise of sleep movement.