Health Disparities in Prevalence of Hypertension Between Black and White Americans

Study Overview
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Brief Summary
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This study will be the first to distinguish the relative contributions of sleep, circadian and behavioral mechanisms to the non-dipping BP profile in Black adults and will lay the groundwork for optimizing therapies dependent on mechanisms, such as targeting sleep, targeting circadian rhythmicity, or targeting behaviors, and raising the possibility that ideal therapy for hypertension (HTN) may differ by race. This research will ultimately help to improve health and survival in black populations with HTN.

Detailed Description
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By studying standardized behaviors and regulators of BP during sleep and behavioral stresses across all circadian phases, this protocol will allow us specifically to: To determine if poor sleep, while controlling for circadian phase, contributes to the higher overall BP and reduced nocturnal drop in BP in Blacks compared to Whites. To determine if reduced BP responses to standardized behavioral changes across the day and night contribute to the higher overall BP and reduced nocturnal drop in BP in Blacks compared to Whites. To determine if reduced circadian amplitude of BP contributes to the higher overall BP and reduced nocturnal drop in BP in Blacks compared to Whites.

Official Title
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Sleep and Circadian Mechanisms Contributing to Disparity in Prevalence of Hypertension Between Black and White Americans

Conditions
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Hypertension, Cardiovascular Risk Factor

Intervention / Treatment
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* Behavioral: Forced Desynchrony


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Self-identified Black or White 'normotensive' (resting systolic blood pressure (SBP) <140/90 mmHg) or uncomplicated stage 1 'hypertensive' (systolic BP between 140 and 160 mmHg or a diastolic (DBP) between 90 and 100 mmHg). free of all prescription and non-prescription drugs (including caffeine, nicotine, alcohol and herbal medications) Exclusion Criteria: Currently treated with pharmacologic agents for hypertension Blood pressure >160/100 mmHg Smoked within the last year Regular night work or rotating shift work for the three months prior to the study Travel across more than three time zones during the three months prior to the study. Any acute, chronic or debilitating medical conditions, other than mild hypertension (140<SBP<160 or 90<DBP<100 mmHg) and severe renal disease (glomerular filtration rate <30) Moderate to severe obstructive sleep apnea (OSA) History of severe psychiatric illnesses or psychiatric disorders will be excluded, including alcoholism, drug dependency, major depression, manic depressive illness, schizophrenic disorders, panic disorder, generalized anxiety disorder, post-traumatic stress disorder, agoraphobia, claustrophobia, paranoid personality disorder, schizoid personality disorder, schizotypal personality disorder, borderline personality disorder, and antisocial personality disorder.

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Forced Desynchrony<br>All participants will undergo a forced desynchrony protocol. | Behavioral: Forced Desynchrony<br>* All sleep opportunities and other activities will be scheduled by the experimenter so that by the end of the study these activities are spread evenly across all phases of the internal body clock.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood pressure | Blood pressure will be measured via automatic and manual-operated sphygmomanometer. Readings will be recorded in units of mmHg. | 7-day lab stay | 
| Heart rate variability | Two channel ECG will be recorded for heart rate variability analysis. | 7-day lab stay | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| venous epinephrine | Venous epinephrine will be measured for adrenal cortex contribution to sympathetic activity. | 7-day lab stay | 
| venous norepinephrine | venous norepinephrine will be measured for sympathetic nerve activity's contribution to sympathetic activity. | 7-day lab stay | 
| saliva cortisol | Saliva cortisol will be measured as a sympathetic potentiating hormone. | 7-day lab stay | 
| saliva melatonin | saliva melatonin will be measured as a sympathetic attenuating hormone. | 7-day lab stay | 
| venous aldosterone | venous aldosterone will be measured as an end point of renin-angiotensin and sympathetic nerve activation | 7-day lab stay | 
| venous endocannabinoids | venous endocannabinoids will be measured to estimate stress habituation. | 7-day lab stay | 
| flow mediated dilation | Flow mediated dilation will be measured as an indication of endothelial function. | 7-day lab stay | 
| beat-by-beat blood pressure | Beat-by-beat Blood Pressure will be measured in the fingers using a non-invasive blood pressure monitoring device. | 7-day lab stay | 
| 24-hr ambulatory blood pressure | Ambulatory blood pressure will be measured with an automatic 24-hr blood pressure monitoring device to estimate of blood pressure dipping status. | 2 day ambulatory period | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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circadian rhythm