Sleep and Circadian Mechanisms in Hypertension

Not Applicable

Recruiting

• Conditions: Cardiovascular Diseases; Circadian Rhythms; Sleep; Hypertension; Cardiovascular Risk Factors
• Interventions: Other: At-home Polysomnography; Other: Circadian Protocol; Other: Rested Wakefulness Trial; Other: Overnight Sleep Trial; Behavioral: Regularized Sleep Schedule

• Registration Number: NCT05184933
• Lead Sponsor: Oregon Health and Science University

Brief Summary

This study is a mechanistic clinical trial designed to investigate the effects of the circadian system and sleep on non-dipping blood pressure (BP) in people with hypertension (HTN).

Detailed Description

This study is a mechanistic clinical trial designed to study the effects of the circadian system and sleep on non-dipping blood pressure (BP) in people with hypertension (HTN). Investigators will study participants with dipping and non-dipping hypertension. All participants will partake in all experiments. First, investigators will assess sleep in the participants' home environment using unattended polysomnography. Participants will then complete a 5-day overnight forced desynchrony laboratory protocol to uncover circadian rhythms (Constant Routine). The second experiment is a randomized crossover protocol. Two trials (Overnight Sleep and Rested Wakefulness) will be completed in randomized order to separate the effects of sleep on non-dipping blood pressure while assessing nighttime cardiovascular mechanisms. Finally, investigators will pilot test if 2 weeks of sleep regularization impacts 24-hour BP.

Study Timeline

• Study First Submitted: 2021-12-22
• Study First Submitted QC: 2021-12-22
• Study First Posted: 2022-01-11
• Study Start: 2022-08-04
• Status Verified: 2025-03
• Last Update Submitted: 2025-03-18
• Last Update Posted: 2025-03-21
• Primary Completion: 2027-03-31
• Study Completion: 2028-03-30

Recruitment & Eligibility

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

Inclusion Criteria

• Ages 25-64
• BMI 18.5-42kg/m2
• Hypertension (average resting blood pressure between 130/80 mmHg and 160/100 mmHg)

Exclusion Criteria

• Over 5 pack-years of smoking;
• Prior shift work within 12 months prior to the study;
• Travel greater than three time zones for at least 3 months;
• History of heart failure, cardiomyopathy, or history of bypass surgery, angioplasty, or previous myocardial infarction;
• Acute or chronic diseases (except hypertension) that may affect outcome measures;
• History of psychological conditions;
• Sleep disorders, like severe sleep apnea, insomnia, etc.;
• Prescription medications (Contraceptives and anti-hypertensive medications are permissible);
• History of Illicit drug use and alcohol dependency;
• 30 days free of cannabis use prior to the study;
• Pregnancy;
• Upper cut-off of 160/100 mmHg for BP

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Dipping vs non-dipping HTN	Circadian Protocol	Participants will wear an ambulatory blood pressure monitor (SpaceLabs, Inc.) which will take their blood pressure in 20-30-minute intervals for 24-48 hours to determine blood pressure dipping status. All participants in this arm will complete the experiments in this order: 1. At-home polysomnography; 2. Constant Routine protocol; 3. Rested Wakefulness Trial AND Overnight Sleep Trial (Randomized crossover); 4. Sleep Regularization Trial
Dipping vs non-dipping HTN	Overnight Sleep Trial	Participants will wear an ambulatory blood pressure monitor (SpaceLabs, Inc.) which will take their blood pressure in 20-30-minute intervals for 24-48 hours to determine blood pressure dipping status. All participants in this arm will complete the experiments in this order: 1. At-home polysomnography; 2. Constant Routine protocol; 3. Rested Wakefulness Trial AND Overnight Sleep Trial (Randomized crossover); 4. Sleep Regularization Trial
Dipping vs non-dipping HTN	At-home Polysomnography	Participants will wear an ambulatory blood pressure monitor (SpaceLabs, Inc.) which will take their blood pressure in 20-30-minute intervals for 24-48 hours to determine blood pressure dipping status. All participants in this arm will complete the experiments in this order: 1. At-home polysomnography; 2. Constant Routine protocol; 3. Rested Wakefulness Trial AND Overnight Sleep Trial (Randomized crossover); 4. Sleep Regularization Trial
Dipping vs non-dipping HTN	Rested Wakefulness Trial	Participants will wear an ambulatory blood pressure monitor (SpaceLabs, Inc.) which will take their blood pressure in 20-30-minute intervals for 24-48 hours to determine blood pressure dipping status. All participants in this arm will complete the experiments in this order: 1. At-home polysomnography; 2. Constant Routine protocol; 3. Rested Wakefulness Trial AND Overnight Sleep Trial (Randomized crossover); 4. Sleep Regularization Trial
Dipping vs non-dipping HTN	Regularized Sleep Schedule	Participants will wear an ambulatory blood pressure monitor (SpaceLabs, Inc.) which will take their blood pressure in 20-30-minute intervals for 24-48 hours to determine blood pressure dipping status. All participants in this arm will complete the experiments in this order: 1. At-home polysomnography; 2. Constant Routine protocol; 3. Rested Wakefulness Trial AND Overnight Sleep Trial (Randomized crossover); 4. Sleep Regularization Trial

Primary Outcome Measures

Name	Time	Method
Heart rate variability (Circadian and Overnight sleep vs. rested wakefulness trial)	7 days	For the duration of all in-laboratory studies, three channels of EKG are recorded (RA-V6) and stored at a sampling frequency of 256 Hz. This software will be used for peak detection (R-wave detection and subsequent heart rate variability (HRV) analysis to estimate cardiac vagal tone). Investigators will study circadian rhythms in heart rate between people with dipping vs non-dipping hypertension. Investigators will also study how overnight sleep affects heart rate variability in these groups. This is a measure of cardiac parasympathetic activity and cardiovascular health.
Norepinephrine (Circadian and Overnight sleep vs. rested wakefulness trial)	7 days	Plasma norepinephrine (measured in plasma according to laboratory values) will be measured to estimate sympathetic output (stress). Higher values may indicate increased cardiovascular risk. Investigators will study circadian rhythms in Norepinephrine between people with dipping vs non-dipping hypertension. Investigators will also study how overnight sleep affects Norepinephrine in these groups.
Sleep Episodes (At-home Polysomnography)	1-2 nights	Sleep episodes will be polysomnographically recorded and scored in 30-sec epochs for sleep stage, arousals, and respiratory events on SomnoMedics Domino Software. Values (based on software analysis) provide a description of what aspects of sleep are different between participants.
Sleep duration (At-home Polysomnography)	1-2 nights	Sleep duration will be scored from the ActiGraph and correlated with the sleep and activity diary. Sleep duration measures the amount of time asleep (in minutes).
Muscle sympathetic nerve activity (MSNA) (Overnight sleep vs. rested wakefulness trial and circadian trial)	7 days	MSNA may be directly measured by inserting a tungsten microelectrode (Frederick Haer, Bowdoinham, ME) into a peroneal nerve at the popliteal fossa. A reference electrode will be inserted subcutaneously 2-3 cm from the recording electrode. Both electrodes will be connected to a differential preamplifier and then to an amplifier to obtain mean voltage neurograms. Once investigators have confirmed a satisfactory post-ganglionic MSNA recording, the participants will be provided a 10 min non-recorded rest to ensure baseline levels. Data will be recorded using WinDaq/Pro data acquisition software (DATAQ Instruments, Akron, OH) and imported for analysis in the commercially available WinCPRS software program (Absolute Aliens; Turku, Finland). Investigators will also study how overnight sleep affects MSNA in these groups. Investigators may also study circadian rhythms in MSNA between people with dipping vs non-dipping hypertension.
Vascular endothelial function (Circadian and Overnight sleep vs. rested wakefulness trial)	7 days	Investigators will measure endothelial function as flow-mediated dilation (FMD). Investigators will measure brachial artery FMD using standard procedures every 3 hours in the constant routine protocol and while awake during the overnight sleep vs. rested wakefulness trial. Investigators will also normalize FMD to the hyperemic shear. Investigators will study circadian rhythms in vascular function in people with dipping vs non-dipping hypertension. Investigators will also study if overnight sleep changes morning vascular function between these groups. Vascular function may be an indicator of cardiovascular health.
Magnitude of overnight blood pressure dipping (Overnight sleep vs. rested wakefulness trial)	2 days	Blood Pressure (BP) dipping will be calculated as the percent reduction in average nighttime BP reduction compared to daytime BP. Both systolic and diastolic blood pressure will be measured in mmHg. Blood pressure dipping status may be an indicator of cardiovascular health. Investigators will study whether being asleep or not changes the magnitude of dipping between dipping and non-dipping hypertension. Investigators will also measure ancillary variables such as average daytime BP, night time BP, and morning surge in BP.
Blood pressure (Circadian and Overnight sleep vs. rested wakefulness trial)	7 days	Blood pressure (BP; systolic and diastolic) will be measured in a supine or semi-recumbent position. Investigators will measure beat-by-beat BP using a noninvasive device employing the volume-clamp method with hydrostatic correction. Investigators will measure BP using a calibrated sphygmomanometer to record sporadic BP at regular intervals throughout the protocols. Investigators will study circadian rhythms in blood pressure between people with dipping vs non-dipping hypertension. Investigators will also study how overnight sleep affects blood pressure in these groups. Investigators will also study ancillary variables such as morning surge in blood pressure. All blood pressure measurements will be measured in mmHg.
Heart rate (Circadian and Overnight sleep vs. rested wakefulness trial)	7 days	Heart rate will be measured in beats-per-minute (bpm). This is a standard marker of cardiovascular health.
Epinephrine (Circadian and Overnight sleep vs. rested wakefulness trial)	7 days	Plasma epinephrine (measured in plasma according to laboratory values) will be measured to estimate sympathetic output (stress). Higher values may indicate increased cardiovascular risk. Investigators will study circadian rhythms in Epinephrine between people with dipping vs non-dipping hypertension. Investigators will also study how overnight sleep affects Epinephrine in these groups.
Aldosterone (Circadian and Overnight sleep vs. rested wakefulness trial)	7 days	Plasma aldosterone (measured in plasma according to laboratory values) will be measured to estimate sympathetic output (stress). Higher values may indicate increased cardiovascular risk. Investigators will study circadian rhythms in Aldosterone between people with dipping vs non-dipping hypertension. Investigators will also study how overnight sleep affects Aldosterone in these groups.
Renin (Circadian and Overnight sleep vs. rested wakefulness trial)	7 days	Plasma renin/activity (measured in plasma according to laboratory values) will be measured to estimate sympathetic output (stress). Higher values may indicate increased cardiovascular risk. Investigators will also study circadian rhythms in renin between people with dipping vs non-dipping hypertension. Investigators will also study how overnight sleep affects renin in these groups.

Secondary Outcome Measures

Name	Time	Method
Blood pressure dipping status (Sleep regularization trial)	2 weeks	Participants will be instructed to select a preferred bedtime time and ensure adherence to that time for 2-weeks. Investigators will not control sleep duration. Both systolic and diastolic blood pressure will be measured in mmHg. Blood pressure dipping status will be assessed. BP dipping will be calculated as the percent reduction in average nighttime BP reduction compared to daytime BP. Blood pressure dipping status may be an indicator of cardiovascular health.
Ambulatory blood pressure (Sleep regularization trial)	2 weeks	Participants will be instructed to select a preferred bedtime time and ensure adherence to that time for 2-weeks. Investigators will not control sleep duration. After this trial, investigators will again measure 24-48 hour ambulatory BP. Both systolic and diastolic blood pressure will be measured in mmHg. Blood pressure dipping status will be assessed. BP dipping will be calculated as the percent reduction in average nighttime BP reduction compared to daytime BP. Blood pressure may be an indicator of cardiovascular health.

Trial Locations

Locations (1)

Oregon Health and Science University; 🇺🇸 Portland, Oregon, United States