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.
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
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
32
Constant routine protocols are used in circadian research to examine underlying circadian rhythms in the absence of light, activity, and meals
University of Alabama at Birmingham
Birmingham, Alabama, United States
Melatonin phase
Circadian phase of melatonin obtained from saliva
Time frame: Melatonin phase during a 30-hour constant routine protocol
Melatonin amplitude
Circadian amplitude of melatonin obtained from saliva
Time frame: Melatonin amplitude during a 30-hour constant routine protocol
Core body temperature phase
Circadian phase of core body temperature recorded and transmitted wirelessly
Time frame: 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
Time frame: 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
Time frame: Expression of Bmal1 and Period 3 during a 30-hour constant routine protocol
Cortisol phase
Circadian phase of cortisol obtained rom saliva
Time frame: Cortisol phase during a 30-hour constant routine protocol
Cortisol amplitude
Circadian amplitude of cortisol obtained rom saliva
Time frame: Cortisol amplitude during a 30-hour constant routine protocol
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