Circadian Mechanisms Underlying Non-Dipping Blood Pressure in Blacks

Not Applicable

Completed

• Conditions: Blood Pressure; Circadian Rhythm
• Interventions: Other: Constant Routine Protocol

• Registration Number: NCT03934255
• Lead Sponsor: University of Alabama at Birmingham

Brief Summary

This study seeks to examine central and peripheral circadian mechanisms in Blacks with appropriately dipping systolic blood pressure (blood pressure that dips by at least 10%) compared with non-dipping systolic blood pressure (blood pressure that dips by less than 10%) using a constant routine protocol. Constant routine protocols are commonly used in the field of circadian biology to examine rhythms in biological processes while controlling the entraining effects of light, activity, and diet.

Detailed Description

This study will enroll a total of 40 participants (n=20 non-dippers; n=20 dippers) to complete a 30-hour constant routine protocol. Participants will undergo baseline testing that includes anthropometric measurements, clinic blood pressure measurements, completion of self-report questionnaires on sleep and mood, be fitted with an ambulatory blood pressure monitor and actigraphy watch, and be provided with home sleep testing (HST) equipment.

Following completion of baseline assessment, eligible participants will be scheduled for the 30-hour constant routine protocol. The 30-hour constant routine protocol will allow for the hourly collection of saliva, collection of buccal cells every 4 hours, and constant monitoring of core body temperature, all of which are primary outcomes in the assessment of central and peripheral circadian clock markers. Amplitude and phase of these outcomes will be assessed in non-dippers versus dippers.

Study Timeline

• Study First Submitted: 2019-04-19
• Study First Submitted QC: 2019-04-29
• Study First Posted: 2019-05-01
• Study Start: 2020-01-01
• Primary Completion: 2023-05-01
• Study Completion: 2023-05-01
• Status Verified: 2023-06
• Last Update Submitted: 2023-06-07
• Last Update Posted: 2023-06-08

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 32

Inclusion Criteria

• Black or African American race
• Age 18 years or older

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Exclusion Criteria

• Work alternating or night shifts
• Pregnant or nursing
• Current illicit drug use
• History of severe mental illness
• Medical conditions that would be contraindicated for a constant routine protocol
• Take anti-hypertensive medications or beta-blockers
• Severe obstructive sleep apnea

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Constant Routine Protocol	Constant Routine Protocol	Participants will be kept in constant conditions for 30 hours to observe circadian physiology in the absence of light, physical activity, and meals.

Primary Outcome Measures

Name	Time	Method
Core body temperature amplitude	Core body temperature amplitude during a 30-hour constant routine protocol	Circadian amplitude of core body temperature recorded and transmitted wirelessly
Melatonin phase	Melatonin phase during a 30-hour constant routine protocol	Circadian phase of melatonin obtained from saliva
Melatonin amplitude	Melatonin amplitude during a 30-hour constant routine protocol	Circadian amplitude of melatonin obtained from saliva
Core body temperature phase	Core body temperature phase during a 30-hour constant routine protocol	Circadian phase of core body temperature recorded and transmitted wirelessly
Buccal cell mRNA expression	Expression of Bmal1 and Period 3 during a 30-hour constant routine protocol	Expression of Bmal1 and Period 3 obtained from buccal cell mRNA

Secondary Outcome Measures

Name	Time	Method
Cortisol phase	Cortisol phase during a 30-hour constant routine protocol	Circadian phase of cortisol obtained rom saliva
Cortisol amplitude	Cortisol amplitude during a 30-hour constant routine protocol	Circadian amplitude of cortisol obtained rom saliva

Trial Locations

Locations (1)

University of Alabama at Birmingham; 🇺🇸 Birmingham, Alabama, United States