Circadian Mechanisms Underlying Non-Dipping Blood Pressure in Blacks

Central and Peripheral Circadian Mechanisms Underlying Non-Dipping Blood Pressure in Blacks

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.

Study Overview

• Status: Completed
• Conditions: Blood Pressure; Circadian Rhythm
• Intervention / Treatment: Other: Constant Routine Protocol

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 Type: Interventional
• Enrollment (Actual): 32
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Stephen J Thomas, PhD; Phone Number: 205-934-3367; Email: sjthoma@uabmc.edu

Study Locations

• United States
  • Alabama
    • Birmingham, Alabama, United States, 35294-0017
      • University of Alabama at Birmingham

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

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

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 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.	Other: Constant Routine Protocol; Constant routine protocols are used in circadian research to examine underlying circadian rhythms in the absence of light, activity, and meals

What is the study measuring?

Primary Outcome Measures

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

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cortisol phase	Circadian phase of cortisol obtained rom saliva	Cortisol phase during a 30-hour constant routine protocol
Cortisol amplitude	Circadian amplitude of cortisol obtained rom saliva	Cortisol amplitude during a 30-hour constant routine protocol

Collaborators and Investigators

• Sponsor: University of Alabama at Birmingham
• Collaborators: American Heart Association

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2020
• Primary Completion (Actual): May 1, 2023
• Study Completion (Actual): May 1, 2023

Study Registration Dates

• First Submitted: April 19, 2019
• First Submitted That Met QC Criteria: April 29, 2019
• First Posted (Actual): May 1, 2019

Study Record Updates

• Last Update Posted (Actual): June 8, 2023
• Last Update Submitted That Met QC Criteria: June 7, 2023
• Last Verified: June 1, 2023

More Information

Terms related to this study

• Other Study ID Numbers: IRB-300003266

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Details regarding sharing IPD are undecided. Protocols and consent forms will be shared. Requests may be made to the study PI.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No