The Circadian Rhythm for Sleep digital therapeutic for insomnia: Conceptual background and single-arm feasibility study

Mar 9, 2026Digital health

Digital sleep therapy based on body clock timing for insomnia: background and initial feasibility study

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Circadian Biology on OpenScience ↗PubMed ↗DOI ↗OA ↗

Abstract

Twenty-three participants were enrolled, with an 87.0% completion rate.

Twenty participants completed the six-week program, and 16 met the data-fidelity criteria for analysis.
Valid passive sensor data were captured on 88.6% of study days, indicating good adherence to the intervention.
Insomnia Severity Index scores significantly improved from a median of 21.0 at baseline to 14.0 by Week 6.
Pittsburgh Sleep Quality Index scores also showed significant improvement, decreasing from a mean of 10.9 to 7.7.
Objective sleep metrics, including total sleep time and sleep onset, did not show significant changes over the study period.
Participant satisfaction with the program was high, with a mean score of 37.9 out of 45.

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OBJECTIVE: To assess the feasibility, acceptability, and preliminary effects of circadian rhythm for sleep (CRS), a mobile digital therapeutic that delivers closed-loop, wearable- and light-sensor-driven circadian coaching for insomnia.

METHODS: Six-week, single-arm feasibility study in adults with short-term or chronic insomnia. CRS provided daily recommendations emphasizing stable wake-up time, morning light exposure, and daytime activity. Feasibility and acceptability outcomes were assessed (completion, passive-sensor data capture/adherence, satisfaction), and the primary clinical outcome (exploratory) was change in Insomnia Severity Index (ISI) from baseline to Week 6; the key secondary clinical outcome (exploratory) was Pittsburgh Sleep Quality Index (PSQI). Objective sleep-wake metrics from wearable device were explored.

RESULTS: Twenty-three participants were enrolled; 20 completed the program (87.0%), and 16 comprised the prespecified analysis set based on data-fidelity criteria. Among these 16 participants, valid passive sensor data from the wearable and light sensors were captured on 88.6% of study days. ISI significantly improved from baseline to Week 6 (median 21.0 → 14.0; < .001 by within-subject analysis), and PSQI improved (mean 10.9 → 7.7; < .001; partial η≈ 0.50). Objective wearable metrics (total sleep time, time-in-bed, sleep onset, wake time) did not change significantly over time in this short pilot. Satisfaction was favorable (mean 37.9/45). No adverse events occurred. p p2

CONCLUSIONS: CRS was feasible and acceptable, and was associated with within-subject improvements in subjective insomnia symptoms in this single-arm feasibility study; however, because there was no control group, these findings are preliminary and hypothesis-generating, supporting further evaluation in larger randomized controlled trials.

TRIAL REGISTRY NAME: Clinical Research Information Service.

URL: https://cris.nih.go.kr.

TRIAL REGISTRATION NUMBER: KCT0010801.

Key numbers

21.0 → 14.0

ISI Improvement

Median ISI score change from baseline to Week 6

37.9/45

Satisfaction Score

Mean satisfaction score among participants who completed the program

88.6%

Data Capture Rate

Percentage of study days with valid sensor data captured

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The Circadian Rhythm for Sleep digital therapeutic for insomnia: Conceptual background and single-arm feasibility study

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