Mood DisordersCaleraNCT07905378
Validation of Wearable Core Body Temperature-Based Circadian Rhythm Digital Biomarkers
An observational study of Mood Disorders and Major Depressive Diorder, run by Korea University Anam Hospital.
Trial summary
This single-site prospective observational study aims to validate wearable-derived circadian and behavioral rhythm biomarkers using continuous core body temperature and raw accelerometry measurements and to explore longitudinal changes in circadian and rest-activity rhythms in psychiatric inpatients. Read more about this study
- Who is it for?
- Ages 19 to 75 yearsHealthy volunteers can take part
- Conditions the study is for
- Mood Disorders, Major Depressive Diorder, Bipolar Disorders
- How many people
- 200 participants
- Where
- No sites listed yet
- Study dates
- 1 Nov 2026to 31 Dec 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 19 to 75 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: This study will enroll 200 adults aged 19-75 years at Korea University Anam Hospital. Study 1 will include 75 outpatients with major depressive disorder, bipolar I disorder, or bipolar II disorder and 75 healthy control participants without a history of psychiatric diagnosis or treatment and without a major mood disorder identified on structured diagnostic assessment. Participants in Study 1 will undergo concurrent monitoring with CALERAResearch and Fitbit devices for approximately 7 days, and a subset of 50 participants will undergo repeat monitoring after an interval of at least 1 month. Study 2 will include 50 patients admitted to the psychiatric inpatient unit for psychiatric treatment, regardless of final psychiatric diagnosis at the time of enrollment. These participants will undergo repeated wearable monitoring during the inpatient observation period.
Who may be able to join
- Adults aged 19-75 years.
- Meets DSM-5 criteria for major depressive disorder, bipolar I disorder, or bipolar II disorder based on a structured diagnostic interview and clinical assessment, with a history of psychiatric consultation for related symptoms.
- Agrees to wear both the core body temperature sensor and wrist-worn wearable device for approximately 7 days.
- Study 1 - Healthy control group
- Adults aged 19-75 years.
- Has no history of psychiatric diagnosis or treatment and is not identified as having a major mood disorder on structured diagnostic assessment.
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- Agrees to wear both the core body temperature sensor and wrist-worn wearable device for approximately 7 days.
- Study 2 - Psychiatric inpatient group
- Adults aged 19-75 years.
- Admitted to the psychiatric inpatient unit of Korea University Anam Hospital for psychiatric treatment; a confirmed final diagnosis is not required at enrollment.
- Agrees to continuously wear the core body temperature sensor and Fitbit during the inpatient study period.
Who cannot join
- History of moderate or severe intellectual disability.
- Current or previous head trauma associated with loss of consciousness, degenerative neurological disease, or organic neurological disorder.
- Shift work, including night work, within the preceding 3 months.
- Travel across three or more time zones within the preceding 2 weeks.
- Fever (body temperature ≥37.5°C) or acute infection at the start of measurement.
- Pregnancy or breastfeeding.
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- Skin disease at the sensor attachment site, history of allergy to medical adhesives, or another condition making sensor attachment inappropriate.
- Difficulty reading or understanding Korean.
- Considered unsuitable for study participation by the principal investigator.
- Study 1 - Healthy control group
- History of clinically significant mood symptoms, defined as previous diagnosis or treatment for a mood disorder or evidence of a past or current major depressive, manic, or hypomanic episode on structured or screening assessment.
- Current use of sleep medications or psychotropic medications, including antidepressants, mood stabilizers, antipsychotics, or benzodiazepines.
- History of moderate or severe intellectual disability.
- Current or previous head trauma associated with loss of consciousness, degenerative neurological disease, or organic neurological disorder.
- Shift work, including night work, within the preceding 3 months.
- Travel across three or more time zones within the preceding 2 weeks.
- Fever (body temperature ≥37.5°C) or acute infection at the start of measurement.
- Pregnancy or breastfeeding.
- Skin disease at the sensor attachment site, history of allergy to medical adhesives, or another condition making sensor attachment inappropriate.
- Difficulty reading or understanding Korean.
- Study 2 - Psychiatric inpatient group
- An acute safety concern, including risk of harm to self or others, that makes wearable monitoring or study assessment inappropriate.
- Lack of capacity to provide informed consent or difficulty providing voluntary informed consent.
- History of moderate or severe intellectual disability.
- Current or previous head trauma associated with loss of consciousness, degenerative neurological disease, or organic neurological disorder.
- Fever (body temperature ≥37.5°C) or acute infection at the start of measurement.
- Pregnancy or breastfeeding.
- Skin disease or history of allergy to medical adhesives that makes sensor attachment inappropriate.
- Difficulty reading or understanding Korean.
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: Validation of Wearable Core Body Temperature Signal-Based Circadian Rhythm Digital Biomarkers
This single-site prospective observational study aims to validate wearable-derived circadian and behavioral rhythm biomarkers using continuous core body temperature and raw accelerometry measurements and to explore longitudinal changes in circadian and rest-activity rhythms in psychiatric inpatients.
The study consists of two complementary substudies. Study 1 will enroll 150 outpatients and community participants, including 75 patients with major depressive disorder or bipolar I/II disorder and 75 healthy controls. Participants will simultaneously wear a CALERAResearch core body temperature sensor and a Fitbit Charge 6 for approximately 7 days. Agreement between Fitbit-derived circadian and sleep/activity rhythm features and CALERAResearch-derived core body temperature and raw accelerometry markers will be evaluated. A subset of 50 participants will undergo a second measurement at least 1 month later to assess test-retest reliability.
Study 2 will enroll 50 psychiatric inpatients irrespective of final diagnosis. Participants will continuously wear CALERAResearch and Fitbit devices from shortly after admission through the inpatient observation period, with CALERAResearch sensors replaced approximately every 5-7 days. Longitudinal changes in core body temperature rhythms, rest-activity rhythms, and physiological-behavioral rhythm alignment will be examined in relation to changes in psychiatric symptoms.
Read the detailed description
The study is a single-site prospective observational study conducted at Korea University Anam Hospital and consists of two complementary substudies using wearable core body temperature and wrist-worn sensor data.
Study 1 is a validation study designed to evaluate the agreement between circadian and behavioral rhythm features derived from a consumer wrist-worn wearable device (Fitbit Charge 6) and physiological circadian and high-resolution behavioral rhythm markers derived from CALERAResearch. Seventy-five outpatients with DSM-5 major depressive disorder, bipolar I disorder, or bipolar II disorder and 75 healthy control participants will simultaneously wear both devices for approximately 7 days. The primary physiological circadian phase marker is the midpoint of the core body temperature trough. Fitbit-derived circadian phase, sleep, and activity rhythm features will be compared with core body temperature and raw accelerometry-derived measures. A subset of 50 participants will repeat the measurement after an interval of at least 1 month to evaluate test-retest reliability.
Study 2 is a transdiagnostic longitudinal observational study of 50 patients admitted to the psychiatric inpatient unit. Eligibility does not depend on a specific final psychiatric diagnosis. Participants will undergo repeated measurement of core body temperature, raw accelerometry, and Fitbit-derived sleep and activity measures from shortly after admission through the inpatient observation period. CALERAResearch sensors will generally be replaced every 5-7 days. Psychiatric symptoms will be repeatedly assessed using the Montgomery-Åsberg Depression Rating Scale, Young Mania Rating Scale, Brief Psychiatric Rating Scale, and Clinical Global Impression. The study will evaluate within-subject changes in circadian and rest-activity rhythms and physiological-behavioral rhythm alignment in relation to changes in psychiatric symptom severity and clinical course.
No therapeutic intervention is assigned as part of the study, and no randomization or masking is performed.
- Keywords
- Core body temperature, Circadian rhythm, Digital biomarker, Wearable device, Digital phenotyping, Rest-activity rhythm, Circadian phase, Raw accelerometry, Physiological-behavioral misalignment, Mood disorders, Bipolar disorder, Major depressive disorder, Psychiatric inpatients, CALERAResearch, Fitbit
- Medical subject headings
- Mood Disorders, Bipolar Disorder, Mental Disorders, Depressive Disorder, Major
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Outpatient Mood Disorder Group | Adults aged 19-75 years with DSM-5 major depressive disorder, bipolar I disorder, or bipolar II disorder. Participants will simultaneously wear CALERAResearch and Fitbit Charge 6 devices for approximately 7 days for validation of circadian and behavioral rhythm biomarkers. A subset may undergo repeat measurement after at least 1 month. | |
| Healthy Control Group | Adults aged 19-75 years with no history of psychiatric diagnosis or treatment and no major mood disorder identified on structured diagnostic assessment. Participants will simultaneously wear CALERAResearch and Fitbit Charge 6 devices for approximately 7 days. A subset may undergo repeat measurement after at least 1 month. | |
| Psychiatric Inpatient Group | Adults aged 19-75 years admitted to the psychiatric inpatient unit for psychiatric treatment. Enrollment is transdiagnostic and does not require a specific final diagnosis at study entry. Participants will undergo repeated CALERAResearch and Fitbit monitoring during the inpatient observation period. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Circular Correlation Between Fitbit Sleep-Derived eDLMO and CALERAResearch-Derived CBT Trough Midpoint
The relationship between estimated dim light melatonin onset (eDLMO), derived from sleep timing data collected using Fitbit Charge 6, and the core body temperature (CBT) trough midpoint measured using CALERAResearch will be evaluated in Study 1 participants. One circadian phase estimate will be derived for each marker during the 7-day monitoring period. The relationship between the two phase markers will be quantified using the circular-circular correlation coefficient (r), accounting for the 24-hour periodicity of clock time. The coefficient is dimensionless and ranges from -1 to 1, with values closer to 1 indicating stronger positive circular correlation.
Measured: Day 1 through Day 7
Circular Correlation Between Fitbit Heart Rate Cosinor Phase and CALERAResearch-Derived CBT Trough Midpoint
The relationship between the acrophase estimated from 24-hour cosinor fitting of heart rate data collected using Fitbit Charge 6 and the core body temperature (CBT) trough midpoint measured using CALERAResearch will be evaluated in Study 1 participants. One phase estimate will be derived for each marker during the 7-day monitoring period. The relationship between the two phase markers will be quantified using the circular-circular correlation coefficient (r), accounting for the 24-hour periodicity of clock time. The coefficient is dimensionless and ranges from -1 to 1, with values closer to 1 indicating stronger positive circular correlation.
Measured: Day 1 through Day 7
Mean Absolute Difference in Phase Changes Between Fitbit Sleep-Derived eDLMO and CALERAResearch-Derived CBT Trough Midpoint
Agreement in circadian phase changes between Fitbit sleep-derived estimated dim light melatonin onset (eDLMO) and CALERAResearch-derived core body temperature (CBT) trough midpoint will be evaluated in 50 Study 1 participants undergoing repeat monitoring. For each marker, the signed circular phase change between the first and second monitoring periods will be calculated. Agreement will be quantified as the mean absolute circular difference between these phase changes, expressed in hours. Lower values indicate closer agreement in the direction and magnitude of phase changes, independent of systematic differences in absolute phase timing.
Measured: First 7-day monitoring period (Days 1-7) and second 7-day monitoring period (an average of 3 months after baseline)
Mean Absolute Difference in Phase Changes Between Fitbit Heart Rate Cosinor Phase and CALERAResearch-Derived CBT Trough Midpoint
Agreement in circadian phase changes between the acrophase derived from 24-hour cosinor fitting of Fitbit Charge 6 heart rate data and the CALERAResearch-derived core body temperature (CBT) trough midpoint will be evaluated in 50 Study 1 participants undergoing repeat monitoring. For each marker, the signed circular phase change between the two monitoring periods will be calculated. Agreement will be quantified as the mean absolute circular difference between these phase changes, expressed in hours. Lower values indicate closer agreement in the direction and magnitude of phase changes, independent of systematic differences in absolute phase timing.
Measured: First 7-day monitoring period (Days 1-7) and second 7-day monitoring period (an average of 3 months after baseline)
Secondary outcomes (7)
Mean Absolute Difference in Sleep Midpoint Between Fitbit Charge 6 and CALERAResearch
Agreement between sleep midpoint derived from Fitbit Charge 6 sleep data and rest/sleep midpoint estimated from CALERAResearch raw accelerometry will be evaluated during concurrent monitoring in Study 1. The mean absolute circular difference between corresponding midpoint estimates will be calculated and reported in hours. Lower values indicate closer agreement between devices.
Measured: Day 1 through Day 7
Rate of Longitudinal Change in CALERAResearch-Derived Core Body Temperature Trough Midpoint
Core body temperature (CBT) trough midpoint will be derived from continuous CALERAResearch measurements during successive monitoring periods in the inpatient cohort (Study 2). Signed circular phase changes will be calculated while accounting for the 24-hour periodicity of clock time. A longitudinal repeated-measures model will estimate the rate of phase change in relation to days since admission, accounting for within-participant correlation. The outcome will be reported as the estimated phase change per day, expressed in hours/day.
Measured: From study enrollment through study completion, an average of 3 weeks
Rate of Longitudinal Change in CALERAResearch-Derived Core Body Temperature Rhythm Amplitude
Core body temperature (CBT) rhythm amplitude will be derived from continuous CALERAResearch measurements during successive monitoring periods in the inpatient cohort (Study 2). A linear mixed-effects model will estimate the longitudinal rate of change in CBT rhythm amplitude as a function of days since admission, accounting for repeated observations within participants. The outcome will be reported as the regression coefficient, expressed in degrees Celsius per day (°C/day).
Measured: From study enrollment through study completion, an average of 3 weeks
Rate of Longitudinal Change in CALERAResearch-Derived Rest-Activity Rhythm Interdaily Stability
Interdaily stability (IS) of rest-activity rhythms will be calculated from CALERAResearch raw accelerometry during successive monitoring periods in the inpatient cohort (Study 2). IS is a dimensionless nonparametric measure of the regularity of rest-activity patterns across days, with higher values indicating greater day-to-day rhythm stability. A linear mixed-effects model will estimate the longitudinal rate of change in IS as a function of days since admission, accounting for repeated observations within participants. The outcome will be reported as the regression coefficient, expressed in IS units per day.
Measured: From study enrollment through study completion, an average of 3 weeks
Rate of Longitudinal Change in Absolute CBT-to-Rest/Sleep Phase Difference
The physiological-behavioral phase difference will be defined as the absolute circular time difference between the core body temperature (CBT) trough midpoint derived from CALERAResearch temperature recordings and the rest/sleep midpoint derived from CALERAResearch raw accelerometry. The phase difference will be calculated for successive monitoring periods in the inpatient cohort (Study 2) and expressed in hours. A linear mixed-effects model will estimate its rate of change as a function of days since admission, accounting for repeated observations within participants. The outcome will be reported as the regression coefficient, expressed in hours/day.
Measured: From study enrollment through study completion, an average of 3 weeks
Within-Participant Regression Coefficient for BPRS Total Score and CBT-to-Rest/Sleep Phase Difference
General psychiatric symptom severity will be assessed using the Brief Psychiatric Rating Scale (BPRS) total score at baseline and subsequent clinical assessments in the inpatient cohort (Study 2), with higher scores indicating greater psychiatric symptom severity. The physiological-behavioral phase difference will be quantified as the absolute circular time difference, expressed in hours, between the CALERAResearch-derived CBT trough midpoint and raw accelerometry-derived rest/sleep midpoint during the corresponding monitoring periods. A linear mixed-effects model will estimate the within-participant association between phase difference and BPRS total score, separating within-participant from between-participant differences. The outcome will be reported as the within-participant regression coefficient, expressed in BPRS points per hour of phase difference.
Measured: From study enrollment through study completion, an average of 3 weeks
Between-Group Difference in CBT-to-Rest/Sleep Phase Angle Between Mood Disorder Patients and Healthy Controls
The physiological-behavioral phase angle will be defined as the signed circular time difference between the core body temperature (CBT) trough midpoint derived from CALERAResearch temperature measurements and the rest/sleep midpoint derived from CALERAResearch raw accelerometry. One phase-angle estimate will be obtained for each Study 1 participant during the 7-day monitoring period. The outcome will be reported as the signed circular difference between the mean phase angles of participants with mood disorders and healthy controls, expressed in hours. A value of zero indicates no difference in mean phase angle between groups.
Measured: Day 1 through Day 7
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Oct 2026
- Study start1 Nov 2026 (estimated)
- Primary completion31 Dec 2027 (estimated)
- Study completion31 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Mood DisordersStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Other
- Time perspective
- Prospective
- Enrolment
- 200 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Korea University Anam Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Heon-Jeong Lee, MD, PhD, Korea University Anam Hospital
- Investigators
- Heon-Jeong Lee, Professor, Principal investigator, Korea University Anam Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07905378
- Sponsor's protocol ID
- 2026AN0521
- Other IDs
- RS-2024-00469788
- Acronym
- Calera
- Status last verified
- Oct 2026
- First submitted
- 11 Oct 2026
- Last updated
- 29 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 29 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Validation of Wearable Core Body Temperature Signal-Based Circadian Rhythm Digital Biomarkers
- ClinicalTrials.gov ID
- NCT07905378
- Acronym / sponsor ID
- Calera / 2026AN0521
- Keywords
- Core body temperature, Circadian rhythm, Digital biomarker, Wearable device, Digital phenotyping, Rest-activity rhythm, Circadian phase, Raw accelerometry
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 200 participants (estimated)
- Lead sponsor
- Korea University Anam HospitalUniversity, hospital or other
- Study start
- 1 Nov 2026 (estimated)
- Primary completion
- 31 Dec 2027 (estimated)
- Study completion
- 31 Dec 2027 (estimated)
- First posted
- 29 Oct 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This single-site prospective observational study aims to validate wearable-derived circadian and behavioral rhythm biomarkers using continuous core body temperature and raw accelerometry measurements and to explore longitudinal changes in circadian and rest-activity rhythms in psychiatric inpatients.
The study consists of two complementary substudies. Study 1 will enroll 150 outpatients and community participants, including 75 patients with major depressive disorder or bipolar I/II disorder and 75 healthy controls. Participants will simultaneously wear a CALERAResearch core body temperature sensor and a Fitbit Charge 6 for approximately 7 days. Agreement between Fitbit-derived circadian and sleep/activity rhythm features and CALERAResearch-derived core body temperature and raw accelerometry markers will be evaluated. A subset of 50 participants will undergo a second measurement at least 1 month later to assess test-retest reliability.
Study 2 will enroll 50 psychiatric inpatients irrespective of final diagnosis. Participants will continuously wear CALERAResearch and Fitbit devices from shortly after admission through the inpatient observation period, with CALERAResearch sensors replaced approximately every 5-7 days. Longitudinal changes in core body temperature rhythms, rest-activity rhythms, and physiological-behavioral rhythm alignment will be examined in relation to changes in psychiatric symptoms.
Detailed description
The study is a single-site prospective observational study conducted at Korea University Anam Hospital and consists of two complementary substudies using wearable core body temperature and wrist-worn sensor data.
Study 1 is a validation study designed to evaluate the agreement between circadian and behavioral rhythm features derived from a consumer wrist-worn wearable device (Fitbit Charge 6) and physiological circadian and high-resolution behavioral rhythm markers derived from CALERAResearch. Seventy-five outpatients with DSM-5 major depressive disorder, bipolar I disorder, or bipolar II disorder and 75 healthy control participants will simultaneously wear both devices for approximately 7 days. The primary physiological circadian phase marker is the midpoint of the core body temperature trough. Fitbit-derived circadian phase, sleep, and activity rhythm features will be compared with core body temperature and raw accelerometry-derived measures. A subset of 50 participants will repeat the measurement after an interval of at least 1 month to evaluate test-retest reliability.
Study 2 is a transdiagnostic longitudinal observational study of 50 patients admitted to the psychiatric inpatient unit. Eligibility does not depend on a specific final psychiatric diagnosis. Participants will undergo repeated measurement of core body temperature, raw accelerometry, and Fitbit-derived sleep and activity measures from shortly after admission through the inpatient observation period. CALERAResearch sensors will generally be replaced every 5-7 days. Psychiatric symptoms will be repeatedly assessed using the Montgomery-Åsberg Depression Rating Scale, Young Mania Rating Scale, Brief Psychiatric Rating Scale, and Clinical Global Impression. The study will evaluate within-subject changes in circadian and rest-activity rhythms and physiological-behavioral rhythm alignment in relation to changes in psychiatric symptom severity and clinical course.
No therapeutic intervention is assigned as part of the study, and no randomization or masking is performed.
Study design
- Observational model
- Other
- Time perspective
- Prospective
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Outpatient Mood Disorder Group | – | –Adults aged 19-75 years with DSM-5 major depressive disorder, bipolar I disorder, or bipolar II disorder. Participants will simultaneously wear CALERAResearch and Fitbit Charge 6 devices for approximately 7 days for validation of circadian and behavioral rhythm biomarkers. A subset may undergo repeat measurement after at least 1 month. |
| Healthy Control Group | – | –Adults aged 19-75 years with no history of psychiatric diagnosis or treatment and no major mood disorder identified on structured diagnostic assessment. Participants will simultaneously wear CALERAResearch and Fitbit Charge 6 devices for approximately 7 days. A subset may undergo repeat measurement after at least 1 month. |
| Psychiatric Inpatient Group | – | –Adults aged 19-75 years admitted to the psychiatric inpatient unit for psychiatric treatment. Enrollment is transdiagnostic and does not require a specific final diagnosis at study entry. Participants will undergo repeated CALERAResearch and Fitbit monitoring during the inpatient observation period. |
Who may qualify
- Ages
- 19 to 75 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- This study will enroll 200 adults aged 19-75 years at Korea University Anam Hospital. Study 1 will include 75 outpatients with major depressive disorder, bipolar I disorder, or bipolar II disorder and 75 healthy control participants without a history of psychiatric diagnosis or treatment and without a major mood disorder identified on structured diagnostic assessment. Participants in Study 1 will undergo concurrent monitoring with CALERAResearch and Fitbit devices for approximately 7 days, and a subset of 50 participants will undergo repeat monitoring after an interval of at least 1 month. Study 2 will include 50 patients admitted to the psychiatric inpatient unit for psychiatric treatment, regardless of final psychiatric diagnosis at the time of enrollment. These participants will undergo repeated wearable monitoring during the inpatient observation period.
Key inclusion criteria (11 listed)
- Adults aged 19-75 years.
- Meets DSM-5 criteria for major depressive disorder, bipolar I disorder, or bipolar II disorder based on a structured diagnostic interview and clinical assessment, with a history of psychiatric consultation for related symptoms.
- Agrees to wear both the core body temperature sensor and wrist-worn wearable device for approximately 7 days.
- Study 1 - Healthy control group
- Adults aged 19-75 years.
Key exclusion criteria (29 listed)
- History of moderate or severe intellectual disability.
- Current or previous head trauma associated with loss of consciousness, degenerative neurological disease, or organic neurological disorder.
- Shift work, including night work, within the preceding 3 months.
- Travel across three or more time zones within the preceding 2 weeks.
- Fever (body temperature ≥37.5°C) or acute infection at the start of measurement.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Circular Correlation Between Fitbit Sleep-Derived eDLMO and CALERAResearch-Derived CBT Trough Midpoint
Time frame: Day 1 through Day 7
The relationship between estimated dim light melatonin onset (eDLMO), derived from sleep timing data collected using Fitbit Charge 6, and the core body temperature (CBT) trough midpoint measured using CALERAResearch will be evaluated in Study 1 participants. One circadian phase estimate will be derived for each marker during the 7-day monitoring period. The relationship between the two phase markers will be quantified using the circular-circular correlation coefficient (r), accounting for the 24-hour periodicity of clock time. The coefficient is dimensionless and ranges from -1 to 1, with values closer to 1 indicating stronger positive circular correlation.
Circular Correlation Between Fitbit Heart Rate Cosinor Phase and CALERAResearch-Derived CBT Trough Midpoint
Time frame: Day 1 through Day 7
The relationship between the acrophase estimated from 24-hour cosinor fitting of heart rate data collected using Fitbit Charge 6 and the core body temperature (CBT) trough midpoint measured using CALERAResearch will be evaluated in Study 1 participants. One phase estimate will be derived for each marker during the 7-day monitoring period. The relationship between the two phase markers will be quantified using the circular-circular correlation coefficient (r), accounting for the 24-hour periodicity of clock time. The coefficient is dimensionless and ranges from -1 to 1, with values closer to 1 indicating stronger positive circular correlation.
Mean Absolute Difference in Phase Changes Between Fitbit Sleep-Derived eDLMO and CALERAResearch-Derived CBT Trough Midpoint
Time frame: First 7-day monitoring period (Days 1-7) and second 7-day monitoring period (an average of 3 months after baseline)
Agreement in circadian phase changes between Fitbit sleep-derived estimated dim light melatonin onset (eDLMO) and CALERAResearch-derived core body temperature (CBT) trough midpoint will be evaluated in 50 Study 1 participants undergoing repeat monitoring. For each marker, the signed circular phase change between the first and second monitoring periods will be calculated. Agreement will be quantified as the mean absolute circular difference between these phase changes, expressed in hours. Lower values indicate closer agreement in the direction and magnitude of phase changes, independent of systematic differences in absolute phase timing.
Mean Absolute Difference in Phase Changes Between Fitbit Heart Rate Cosinor Phase and CALERAResearch-Derived CBT Trough Midpoint
Time frame: First 7-day monitoring period (Days 1-7) and second 7-day monitoring period (an average of 3 months after baseline)
Agreement in circadian phase changes between the acrophase derived from 24-hour cosinor fitting of Fitbit Charge 6 heart rate data and the CALERAResearch-derived core body temperature (CBT) trough midpoint will be evaluated in 50 Study 1 participants undergoing repeat monitoring. For each marker, the signed circular phase change between the two monitoring periods will be calculated. Agreement will be quantified as the mean absolute circular difference between these phase changes, expressed in hours. Lower values indicate closer agreement in the direction and magnitude of phase changes, independent of systematic differences in absolute phase timing.
7 secondary outcomes
Mean Absolute Difference in Sleep Midpoint Between Fitbit Charge 6 and CALERAResearch
Time frame: Day 1 through Day 7
Rate of Longitudinal Change in CALERAResearch-Derived Core Body Temperature Trough Midpoint
Time frame: From study enrollment through study completion, an average of 3 weeks
Rate of Longitudinal Change in CALERAResearch-Derived Core Body Temperature Rhythm Amplitude
Time frame: From study enrollment through study completion, an average of 3 weeks
Rate of Longitudinal Change in CALERAResearch-Derived Rest-Activity Rhythm Interdaily Stability
Time frame: From study enrollment through study completion, an average of 3 weeks
Rate of Longitudinal Change in Absolute CBT-to-Rest/Sleep Phase Difference
Time frame: From study enrollment through study completion, an average of 3 weeks
Within-Participant Regression Coefficient for BPRS Total Score and CBT-to-Rest/Sleep Phase Difference
Time frame: From study enrollment through study completion, an average of 3 weeks
Between-Group Difference in CBT-to-Rest/Sleep Phase Angle Between Mood Disorder Patients and Healthy Controls
Time frame: Day 1 through Day 7
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Oct 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Heon-Jeong Lee, Professor principal investigator
Korea University Anam Hospital
Questions about this trial
What is this clinical trial studying?
An observational study of Mood Disorders and Major Depressive Diorder, run by Korea University Anam Hospital.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 11 inclusion and 29 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 29 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Soohyun Park, PhD candidate (82+02-920-5507, psh7321@naver.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Circular Correlation Between Fitbit Sleep-Derived eDLMO and CALERAResearch-Derived CBT Trough Midpoint (time frame: Day 1 through Day 7). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Oct 2026.