An observational study in Essential Arterial Hypertension and Circadian Disruption, sponsored by Medical University of Sofia. Active, not recruiting at 1 site in Bulgaria. Open to participants aged 18 Years to 45 Years. Per ClinicalTrials.gov, last updated 2026-08-19.
Sponsored by Medical University of Sofia · Observational
This prospective observational study will investigate whether circadian disruption is associated with higher blood pressure and a less favorable cardiovascular profile in young adults aged 18 to 45 years with essential arterial hypertension. Participants will undergo 14 days of wrist actigraphy using the CamNtech MotionWatch 8, 24-hour ambulatory blood pressure monitoring, cardiovascular assessment, laboratory testing, and validated questionnaires assessing perceived stress and insomnia symptoms. Circadian disruption will be classified using a predefined five-component research index based on actigraphy measures. Participants with three or more abnormal circadian indicators will be classified as Circadian Disruption Index-positive and compared with participants with zero to two abnormal indicators. The primary outcome is mean 24-hour systolic blood pressure. Secondary outcomes include nocturnal blood pressure patterns, cardiac structure and function, heart-rate variability, stress, insomnia symptoms, and individual circadian measures. The Circadian Disruption Index is a study-specific research classification and is not intended to diagnose a circadian rhythm sleep-wake disorder.
This study is designed to investigate the relationship between circadian organization, sleep-wake patterns, and cardiovascular characteristics in young adults with established essential arterial hypertension. The study is based on the hypothesis that circadian disruption may be associated with an adverse cardiovascular phenotype, particularly alterations in the 24-hour blood pressure profile and early markers of cardiovascular remodeling.
Circadian organization will be assessed using prolonged ambulatory wrist actigraphy. A predefined research index will integrate five complementary indicators of circadian rhythmicity and sleep-wake regularity. The index is intended to provide an operational and reproducible classification of the degree of circadian disruption within the study population rather than to establish a clinical diagnosis of a circadian rhythm sleep-wake disorder.
Cardiovascular assessment will include ambulatory blood pressure monitoring, echocardiographic assessment of cardiac structure and function, heart-rate variability, and selected metabolic and inflammatory biomarkers. Psychological and sleep-related factors will also be assessed in order to explore the potential contribution of perceived stress and insomnia symptoms to the relationship between circadian organization and cardiovascular characteristics.
The primary analytical approach will compare participants classified as having a positive Circadian Disruption Index with those classified as negative. Multivariable statistical models will subsequently be used to determine whether the observed association between circadian disruption and cardiovascular parameters persists after adjustment for relevant demographic, anthropometric, hypertension-related, treatment-related, and sleep-related factors.
An additional exploratory objective is to evaluate whether a combination of cardiovascular, metabolic, behavioral, and psychological characteristics can identify participants with a higher probability of circadian disruption. This exploratory analysis may contribute to the development of a preliminary cardiovascular-circadian risk metric that could subsequently be evaluated and validated in independent cohorts.
The study is observational and does not assign participants to a therapeutic intervention. The research classification of circadian disruption should not be interpreted as a diagnosis of a circadian rhythm sleep-wake disorder, and the findings will be interpreted in the context of the overall clinical characteristics of the participants.
6,114 studies on the registry are indexed under Hypertension; 912 are open to participants now.
This study's planned enrollment of 200 is below the median of 350 across 1,163 observational studies indexed under Hypertension.
Browse Hypertension studies →Medical University of Sofia is the lead sponsor of 12 studies on the registry; 1 is open to participants now.
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The study population will consist of adults aged 18 to 45 years with established essential arterial hypertension who meet all predefined eligibility criteria. Participants will be recruited from the clinical population of the participating study center. The study population will include both male and female participants. Individuals with shift work or night-duty work, secondary hypertension, previously diagnosed circadian rhythm sleep-wake disorders, clinically significant sleep-related breathing disorders, diabetes mellitus, significant cardiovascular disease other than uncomplicated essential hypertension, clinically significant renal or endocrine disease, or other conditions likely to substantially affect circadian rhythm or blood pressure measurements will be excluded.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants with three or more abnormal criteria among the five predefined components of the Circadian Disruption Index.
Participants with zero to two abnormal criteria among the five predefined components of the Circadian Disruption Index.
Mean 24-Hour Systolic Blood Pressure
Mean systolic blood pressure over a valid 24-hour ambulatory blood pressure monitoring period performed during the 14-day actigraphy recording period.
Time frame: During the 14-day actigraphy period
Mean 24-Hour Diastolic Blood Pressure
Mean diastolic blood pressure over a valid 24-hour ambulatory blood pressure monitoring period.
Time frame: During the 14-day actigraphy period
Mean Nocturnal Systolic Blood Pressure
Mean systolic blood pressure during the predefined nocturnal period measured by 24-hour ambulatory blood pressure monitoring.
Time frame: During the 14-day actigraphy period
Mean Nocturnal Diastolic Blood Pressure
Mean diastolic blood pressure during the predefined nocturnal period measured by 24-hour ambulatory blood pressure monitoring.
Time frame: During the 14-day actigraphy period
Nocturnal Systolic Blood Pressure Dipping
Percentage reduction in mean nocturnal systolic blood pressure compared with mean daytime systolic blood pressure.
Time frame: During the 14-day actigraphy period
Non-Dipping and Reverse-Dipping Blood Pressure Pattern
Proportion of participants demonstrating a non-dipping or reverse-dipping nocturnal systolic blood pressure pattern based on 24-hour ambulatory blood pressure monitoring.
Time frame: During the 14-day actigraphy period
Left Ventricular Mass Index
Left ventricular mass indexed to body surface area, assessed by transthoracic echocardiography.
Time frame: At baseline assessment
Left Atrial Volume Index
Left atrial volume indexed to body surface area, assessed by transthoracic echocardiography.
Time frame: At baseline assessment
E/e' Ratio
Ratio of early transmitral flow velocity to early diastolic mitral annular velocity as an echocardiographic measure of left ventricular diastolic function.
Time frame: At baseline assessment
Global Longitudinal Strain
Left ventricular global longitudinal strain assessed by transthoracic echocardiography.
Time frame: At baseline assessment
Heart Rate Variability
Heart rate variability assessed using standard time-domain parameters, including SDNN and RMSSD.
Time frame: During the 14-day actigraphy period
Perceived Stress
Perceived psychological stress was assessed using the 10-item Perceived Stress Scale (PSS-10). Each item is rated on a 5-point scale from 0 (never) to 4 (very often), yielding a total score of 0-40. Higher scores indicate greater perceived stress.
Time frame: At baseline assessment
Insomnia Severity
Severity of insomnia symptoms was assessed using the Insomnia Severity Index (ISI), a 7-item questionnaire assessing difficulties with sleep onset, sleep maintenance, early morning awakening, satisfaction with sleep, interference with daily functioning, noticeability of sleep problems, and distress caused by sleep difficulties. Each item is scored from 0 to 4, yielding a total score of 0-28, with higher scores indicating greater insomnia severity. Scores of 0-7 indicate no clinically significant insomnia, 8-14 subthreshold insomnia, 15-21 moderate clinical insomnia, and 22-28 severe clinical insomnia.
Time frame: At baseline assessment
Interdaily Stability
Interdaily Stability (IS) derived from actigraphy to quantify the consistency of the 24-hour activity-rest pattern across monitoring days.
Time frame: During the 14-day actigraphy period
Intradaily Variability
Intradaily Variability (IV) derived from actigraphy to quantify fragmentation of the activity-rest rhythm within individual days.
Time frame: During the 14-day actigraphy period
Relative Amplitude
Relative Amplitude (RA) derived from actigraphy as a measure of the contrast between the most active and least active periods of the 24-hour cycle.
Time frame: During the 14-day actigraphy period
Sleep-Onset Time Variability
Variability in sleep-onset time across the 14-day actigraphy monitoring period, expressed as the standard deviation of sleep-onset time.
Time frame: During the 14-day actigraphy period
Wake-Time Variability
Variability in wake time across the 14-day actigraphy monitoring period, expressed as the standard deviation of wake time.
Time frame: During the 14-day actigraphy period
Plan to share: No — Individual participant data will not be shared with other researchers because the study involves clinical and health-related data collected from a single-center cohort. Data will be used for the analyses specified in the study protocol and will be reported in aggregate form to protect participant confidentiality and privacy.
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This study is active, not recruiting, as verified in Aug 2026. You cannot join it, but the record below documents what was studied.
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Medical University of Sofia