An interventional study of BELL-001 Digital Therapeutic and Sham Digital Therapeutic in Insomnia, sponsored by BELL Therapeutics Inc.. Completed at 1 site in South Korea. Open to participants aged 19 Years to 39 Years. Per ClinicalTrials.gov, last updated 2026-10-22.
Sponsored by BELL Therapeutics Inc. · Not applicable, Interventional, and Basic science
The purpose of this study was to describe how brain activity and heart rhythm respond to BELL-001, a smartphone application that plays sounds linked to the user's own breathing, compared with a sham application that looks the same but does not link its sounds to breathing. Adults with self-reported insomnia symptoms were randomly assigned to BELL-001 or to the sham application. During one laboratory visit, brain activity was recorded with electroencephalography (EEG), heart activity with electrocardiography (ECG), and breathing with a chest belt while participants rested with their eyes closed, then used the assigned application actively for 10 minutes, and then listened passively for 50 minutes. After the visit, all participants, regardless of laboratory group, used the BELL-001 application at home for 7 nights in an open-label period while wearing a smartwatch.
This study was registered retrospectively, in October 2026, after enrollment and data collection (November 2025 to February 2026) had been completed. It was conducted under Korea Institute of Science and Technology (KIST) Institutional Review Board protocol KIST-202411-HR-006, an institutional protocol for non-invasive biosignal research, which was first approved on 25 March 2025, before the first participant was enrolled; an amendment was approved on 12 December 2025. Participants were assigned by computerized randomization stratified by age, sex, Insomnia Severity Index (ISI) score and Epworth Sleepiness Scale (ESS) score. Each participant attended one visit in a sound-attenuated room at KIST, where a short practice with the application and a brief auditory evoked potential recording were followed by a 70-minute recording: eyes-closed rest (10 minutes), an active stage (10 minutes) and a passive stage (50 minutes). After the visit, all participants, regardless of laboratory group, used the BELL-001 application at bedtime for 7 nights in an open-label period while wearing a wrist-worn smartwatch, and then completed the ISI and sleep questions again; home-use outcomes are analyzed as a single group. The outcome measures listed are those analyzed in the resulting publications; analytical details that the IRB-approved protocol did not specify, such as frequency bands, cortical regions, time windows and statistical procedures, were finalized during analysis, and all analyses are reported as exploratory and hypothesis-generating. The clinical efficacy of BELL-001 has been evaluated separately in a multicenter randomized sham-controlled trial (NCT07295431).
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Participants used the BELL-001 smartphone application during one laboratory visit, with sound delivered through insert earphones. After a short practice, a brief auditory evoked potential recording and 10 minutes of eyes-closed rest, participants completed a 10-minute active stage in which they held the touchscreen pressed during each inhalation and released it during each exhalation while the application played sounds that followed this press-and-release signal, and then a 50-minute passive listening stage in which the pace of the sound slowed gradually from the breathing rate established in the active stage. Eyes remained closed throughout the recording. After the visit, participants used BELL-001 at home for 7 nights in an open-label period, as did participants in the sham group.
Device: BELL-001 Digital Therapeutic
Participants used a sham application with the same appearance and screen flow during one laboratory visit, with the same practice, auditory evoked potential recording and 10 minutes of eyes-closed rest. During the 10-minute active stage, they tapped the touchscreen each time they heard a brief tone presented at random intervals of 2 to 12 seconds. During the 50-minute passive stage, a single fixed pre-recorded sound that was not linked to breathing was played. Eyes remained closed throughout the recording. After the visit, participants in this group also used the BELL-001 application (not the sham) at home for 7 nights in an open-label period while wearing a wrist-worn smartwatch.
Device: BELL-001 Digital Therapeutic · Device: Sham Digital Therapeutic
Smartphone-based digital therapeutic that plays sound linked to the user's breathing phase through insert earphones. In this study, the participant's own touchscreen press (inhalation) and release (exhalation) served as the breathing-phase signal during the active stage, followed by a sound sequence that slowed from the breathing rate established in the active stage. A respiration belt was used for recording only and was not an input to the application.
Also known as: BELL-001
Application with the same appearance and screen flow as BELL-001 that plays a single fixed pre-recorded sound not linked to breathing, with brief tones at random intervals during the active stage to match the touch task.
Change in Sensor-Level Electroencephalography (EEG) Power in the Delta Band (0.1 to 4 Hz) From Rest to the Active and Passive Stages
EEG power (microvolts squared) in the delta band (0.1 to 4 Hz) at each of 56 scalp electrodes, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Sensor-Level Electroencephalography (EEG) Power in the Theta Band (4 to 8 Hz) From Rest to the Active and Passive Stages
EEG power (microvolts squared) in the theta band (4 to 8 Hz) at each of 56 scalp electrodes, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Sensor-Level Electroencephalography (EEG) Power in the Alpha Band (8 to 12 Hz) From Rest to the Active and Passive Stages
EEG power (microvolts squared) in the alpha band (8 to 12 Hz) at each of 56 scalp electrodes, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Sensor-Level Electroencephalography (EEG) Power in the Low Alpha Band (8 to 10 Hz) From Rest to the Active and Passive Stages
EEG power (microvolts squared) in the low alpha band (8 to 10 Hz) at each of 56 scalp electrodes, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Sensor-Level Electroencephalography (EEG) Power in the High Alpha Band (10 to 12 Hz) From Rest to the Active and Passive Stages
EEG power (microvolts squared) in the high alpha band (10 to 12 Hz) at each of 56 scalp electrodes, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Sensor-Level Electroencephalography (EEG) Power in the Beta Band (12 to 30 Hz) From Rest to the Active and Passive Stages
EEG power (microvolts squared) in the beta band (12 to 30 Hz) at each of 56 scalp electrodes, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Sensor-Level Electroencephalography (EEG) Power in the Low Beta Band (12 to 20 Hz) From Rest to the Active and Passive Stages
EEG power (microvolts squared) in the low beta band (12 to 20 Hz) at each of 56 scalp electrodes, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Sensor-Level Electroencephalography (EEG) Power in the High Beta Band (20 to 30 Hz) From Rest to the Active and Passive Stages
EEG power (microvolts squared) in the high beta band (20 to 30 Hz) at each of 56 scalp electrodes, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Sensor-Level Electroencephalography (EEG) Power in the Gamma Band (30 to 70 Hz) From Rest to the Active and Passive Stages
EEG power (microvolts squared) in the gamma band (30 to 70 Hz) at each of 56 scalp electrodes, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Sensor-Level Electroencephalography (EEG) Power in the Total Band (0.1 to 70 Hz) From Rest to the Active and Passive Stages
EEG power (microvolts squared) in the total band (0.1 to 70 Hz) at each of 56 scalp electrodes, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Source-Level EEG Functional Connectivity (Weighted Phase Lag Index) in the Delta Band (0.1 to 4 Hz) From Rest to the Active Stage
Weighted phase lag index (wPLI; unitless, range 0 to 1) in the delta band (0.1 to 4 Hz) for each of 1,035 pairs among 46 cortical regions of the Desikan-Killiany atlas, estimated from source-reconstructed EEG, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Source-Level EEG Functional Connectivity (Weighted Phase Lag Index) in the Theta Band (4 to 8 Hz) From Rest to the Active Stage
Weighted phase lag index (wPLI; unitless, range 0 to 1) in the theta band (4 to 8 Hz) for each of 1,035 pairs among 46 cortical regions of the Desikan-Killiany atlas, estimated from source-reconstructed EEG, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Source-Level EEG Functional Connectivity (Weighted Phase Lag Index) in the Alpha Band (8 to 12 Hz) From Rest to the Active Stage
Weighted phase lag index (wPLI; unitless, range 0 to 1) in the alpha band (8 to 12 Hz) for each of 1,035 pairs among 46 cortical regions of the Desikan-Killiany atlas, estimated from source-reconstructed EEG, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Source-Level EEG Functional Connectivity (Weighted Phase Lag Index) in the Low Alpha Band (8 to 10 Hz) From Rest to the Active Stage
Weighted phase lag index (wPLI; unitless, range 0 to 1) in the low alpha band (8 to 10 Hz) for each of 1,035 pairs among 46 cortical regions of the Desikan-Killiany atlas, estimated from source-reconstructed EEG, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Source-Level EEG Functional Connectivity (Weighted Phase Lag Index) in the High Alpha Band (10 to 12 Hz) From Rest to the Active Stage
Weighted phase lag index (wPLI; unitless, range 0 to 1) in the high alpha band (10 to 12 Hz) for each of 1,035 pairs among 46 cortical regions of the Desikan-Killiany atlas, estimated from source-reconstructed EEG, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Source-Level EEG Functional Connectivity (Weighted Phase Lag Index) in the Beta Band (12 to 30 Hz) From Rest to the Active Stage
Weighted phase lag index (wPLI; unitless, range 0 to 1) in the beta band (12 to 30 Hz) for each of 1,035 pairs among 46 cortical regions of the Desikan-Killiany atlas, estimated from source-reconstructed EEG, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Source-Level EEG Functional Connectivity (Weighted Phase Lag Index) in the Low Beta Band (12 to 20 Hz) From Rest to the Active Stage
Weighted phase lag index (wPLI; unitless, range 0 to 1) in the low beta band (12 to 20 Hz) for each of 1,035 pairs among 46 cortical regions of the Desikan-Killiany atlas, estimated from source-reconstructed EEG, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Source-Level EEG Functional Connectivity (Weighted Phase Lag Index) in the High Beta Band (20 to 30 Hz) From Rest to the Active Stage
Weighted phase lag index (wPLI; unitless, range 0 to 1) in the high beta band (20 to 30 Hz) for each of 1,035 pairs among 46 cortical regions of the Desikan-Killiany atlas, estimated from source-reconstructed EEG, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Source-Level EEG Functional Connectivity (Weighted Phase Lag Index) in the Gamma Band (30 to 70 Hz) From Rest to the Active Stage
Weighted phase lag index (wPLI; unitless, range 0 to 1) in the gamma band (30 to 70 Hz) for each of 1,035 pairs among 46 cortical regions of the Desikan-Killiany atlas, estimated from source-reconstructed EEG, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Source-Level EEG Functional Connectivity (Weighted Phase Lag Index) in the Total Band (0.1 to 70 Hz) From Rest to the Active Stage
Weighted phase lag index (wPLI; unitless, range 0 to 1) in the total band (0.1 to 70 Hz) for each of 1,035 pairs among 46 cortical regions of the Desikan-Killiany atlas, estimated from source-reconstructed EEG, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Median of Relative RR Intervals From Rest to the Active and Passive Stages
Median of Relative RR Intervals (percent) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Interquartile Range of Relative RR Intervals From Rest to the Active and Passive Stages
Interquartile Range of Relative RR Intervals (percent) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Mean RR Interval From Rest to the Active and Passive Stages
Mean RR Interval (milliseconds) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Heart Rate From Rest to the Active and Passive Stages
Heart Rate (beats per minute) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Standard Deviation of NN Intervals (SDNN) From Rest to the Active and Passive Stages
Standard Deviation of NN Intervals (SDNN) (milliseconds) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Root Mean Square of Successive Differences (RMSSD) From Rest to the Active and Passive Stages
Root Mean Square of Successive Differences (RMSSD) (milliseconds) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Percentage of Successive RR Intervals Differing by More Than 50 ms (pNN50) From Rest to the Active and Passive Stages
Percentage of Successive RR Intervals Differing by More Than 50 ms (pNN50) (percent) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Heart Rate Variability Triangular Index From Rest to the Active and Passive Stages
Heart Rate Variability Triangular Index (unitless) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Triangular Interpolation of the NN Interval Histogram (TINN) From Rest to the Active and Passive Stages
Triangular Interpolation of the NN Interval Histogram (TINN) (milliseconds) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Poincare Plot Standard Deviation 1 (SD1) From Rest to the Active and Passive Stages
Poincare Plot Standard Deviation 1 (SD1) (milliseconds) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Poincare Plot Standard Deviation 2 (SD2) From Rest to the Active and Passive Stages
Poincare Plot Standard Deviation 2 (SD2) (milliseconds) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in SD1/SD2 Ratio From Rest to the Active and Passive Stages
SD1/SD2 Ratio (unitless ratio) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Normalized Low-Frequency Power (LF) From Rest to the Active and Passive Stages
Normalized Low-Frequency Power (LF) (normalized units) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Normalized High-Frequency Power (HF) From Rest to the Active and Passive Stages
Normalized High-Frequency Power (HF) (normalized units) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Low-Frequency to High-Frequency Power Ratio (LF/HF) From Rest to the Active and Passive Stages
Low-Frequency to High-Frequency Power Ratio (LF/HF) (unitless ratio) derived from the electrocardiogram (ECG) in 3-minute windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Respiratory Rate From Rest to the Active and Passive Stages
Respiratory rate (breaths per minute) derived from the respiration belt in 60-second windows, calculated as the active-stage value minus the resting-stage value and as the passive-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10), active stage (minutes 10 to 20) and passive stage (minutes 20 to 70) of the 70-minute recording in the single laboratory visit
Change in Respiratory Sinus Arrhythmia Amplitude From Rest to the Active Stage
Respiratory sinus arrhythmia amplitude (seconds), defined as the mean per-breath difference between the longest and shortest RR interval, derived from the electrocardiogram (ECG) and respiration-belt signals, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Change in Heartbeat-Evoked Potential Amplitude From Rest to the Active Stage
Mean EEG amplitude (microvolts) from 400 to 550 milliseconds after each electrocardiogram R-peak at frontal electrodes Fpz, Fp1 and Fp2, calculated as the active-stage value minus the resting-stage value, and compared between the BELL-001 and sham groups.
Time frame: Resting stage (minutes 0 to 10) and active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Respiratory Timing Accuracy at Inhalation Onset During the Active Stage
Signed delay (seconds) between each inhalation onset detected from the respiration belt and the corresponding screen press recorded by the application, averaged per participant; assessed in the BELL-001 group only, because the sham task was not linked to breathing.
Time frame: Active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Respiratory Timing Accuracy at Exhalation Onset During the Active Stage
Signed delay (seconds) between each exhalation onset detected from the respiration belt and the corresponding screen release recorded by the application, averaged per participant; assessed in the BELL-001 group only, because the sham task was not linked to breathing.
Time frame: Active stage (minutes 10 to 20) of the 70-minute recording in the single laboratory visit
Self-Reported Total Drowsiness Time During the Laboratory Visit
Total time (minutes) participants reported having been drowsy during the recording, collected by questionnaire immediately after the session, and compared between the BELL-001 and sham groups.
Time frame: Immediately after the 70-minute recording in the single laboratory visit
Perceived Helpfulness of the Assigned Application
Single post-session item asking how helpful the application would be for relieving insomnia, rated from 1 (not at all helpful) to 6 (very helpful); higher scores indicate greater perceived helpfulness; compared between the BELL-001 and sham groups as an indirect check of blinding.
Time frame: Immediately after the 70-minute recording in the single laboratory visit
Change in Insomnia Severity Index (ISI) Total Score From Screening to After 7 Days of Home Use
ISI total score (range 0 to 28; higher scores indicate more severe insomnia), calculated as the score after 7 days of home use of BELL-001 minus the screening score, and analyzed in all participants as a single group (both laboratory groups used BELL-001 at home).
Time frame: Screening (before the laboratory visit) and after 7 days of home use
Change in Self-Reported Sleep Onset Latency From Before to After 7 Days of Home Use
Average time to fall asleep over the previous week (minutes), reported by questionnaire before the laboratory visit and after 7 days of home use, calculated as the post-week value minus the pre-visit value, and analyzed in all participants as a single group (both laboratory groups used BELL-001 at home).
Time frame: Before the laboratory visit and after 7 days of home use
Change in Self-Reported Number of Night Awakenings From Before to After 7 Days of Home Use
Average number of awakenings per night over the previous week, reported by questionnaire before the laboratory visit and after 7 days of home use, calculated as the post-week value minus the pre-visit value, and analyzed in all participants as a single group (both laboratory groups used BELL-001 at home).
Time frame: Before the laboratory visit and after 7 days of home use
Change in Self-Reported Wake Time After Sleep Onset From Before to After 7 Days of Home Use
Average time awake after falling asleep over the previous week (minutes), reported by questionnaire before the laboratory visit and after 7 days of home use, calculated as the post-week value minus the pre-visit value, and analyzed in all participants as a single group (both laboratory groups used BELL-001 at home).
Time frame: Before the laboratory visit and after 7 days of home use
Nightly Mean Heart Rate During Sleep Over 7 Days of Home Use
Mean heart rate during the sleep period of each night (beats per minute), recorded by a wrist-worn smartwatch; the change across nights is analyzed in all participants as a single group (both laboratory groups used BELL-001 at home).
Time frame: Each night during the 7 days of home use after the laboratory visit
Nightly Total Sleep Time Over 7 Days of Home Use
Total sleep time of each night (minutes), estimated by a wrist-worn smartwatch, analyzed in all participants as a single group (both laboratory groups used BELL-001 at home).
Time frame: Each night during the 7 days of home use after the laboratory visit
Daytime Mean Heart Rate Over 7 Days of Home Use
Mean heart rate during waking hours of each day (beats per minute), recorded by a wrist-worn smartwatch, analyzed in all participants as a single group (both laboratory groups used BELL-001 at home).
Time frame: Each day during the 7 days of home use after the laboratory visit
Daily Step Count Over 7 Days of Home Use
Number of steps per day, recorded by a wrist-worn smartwatch, analyzed in all participants as a single group (both laboratory groups used BELL-001 at home).
Time frame: Each day during the 7 days of home use after the laboratory visit
Plan to share: Yes — De-identified participant-level values of the derived measures used in the published analyses (electroencephalography (EEG) spectral power, EEG functional connectivity and heart rate variability features) will be shared on the Open Science Framework upon acceptance of the resulting manuscript. Raw EEG, electrocardiography (ECG) and respiration recordings may be shared with qualified researchers under a data-use agreement, where permitted by participant consent and the data-sharing policies of the Korea Institute of Science and Technology and Hanyang University.
Supporting information: Analytic code
Time frame: Beginning at acceptance of the resulting manuscript, with no planned end date.
Access criteria: Requests from qualified researchers to the corresponding analytical author at Hanyang University; raw data require a data-use agreement.
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