Observational Analytical Validation Study of the Replior ScratchSense

Nocturnal scratching is a frequent and meaningful symptom in dermatological conditions such as atopic dermatitis. It may reflect underlying disease activity and can substantially disrupt overall sleep and quality of life. Existing approaches to characterizing Nocturnal Scratching-such as self-reports, sleep diaries, and video monitoring-are often subjective, labor-intensive, or lack scalability for widespread use. Emerging wearable technologies offer an alternative, by enabling objective, continuous, and non- invasive signal related to scratch behavior during sleep.

Inclusion Criteria: * Male / female participant, aged 18 to 65 years inclusive. Negative pregnancy test at screening for childbearing potential women. Presence of itch-related and/or scratching-inducing conditions: documented or self-reported history of nocturnal itching and scratching, due to conditions such as: * Atopic dermatitis * Chronic pruritus of unknown origin * Other pruritic dermatological or systemic conditions. Expected Nocturnal Scratch activity: participants must: Have experienced Nocturnal Scratching in the past 7 days, and * Be considered likely to scratch during the study period, based on medical history, clinician judgment, or recent self-report Exclusion Criteria: * No current or expected nocturnal itch: well-controlled conditions or no recent reports of nighttime scratching. Confounding movement disorders or sleep conditions: diagnosed restless legs syndrome, periodic limb movement disorder, moderate/severe obstructive sleep apnea, Parkinson's disease, or other conditions that may interfere with motion analysis. Recent changes in anti-pruritic treatment: Initiation or dose changes of systemic medications that may suppress nocturnal itch within the past 2 weeks, including: i. Oral corticosteroids ii. Immunosuppressive agents (e.g., cyclosporine, methotrexate) iii. Biologics (e.g., dupilumab) unless on a stable dose ≥8 weeks iv. Sedating antihistamines unless stable for ≥1 week. Topical treatment use: initiation of topical corticosteroids, calcineurin inhibitors, or emollients within 3 days prior to study start, and no use during the study. Severe psychiatric or cognitive impairment that could impair the ability to consent or comply with the protocol