Sleep and Circadian Rhythm Study for High Blood Pressure

(SCN-BP Trial)

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of Alabama at Birmingham

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 1

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to explore how sleep patterns and body clock rhythms affect nighttime blood pressure levels. Participants will follow a specific routine in a controlled environment, staying awake in dim lighting while researchers monitor their vital signs. This routine is known as the Constant Routine Protocol. The study seeks individuals already participating in a related research project. Those with high blood pressure who are interested in understanding how sleep might affect it may be a good fit. As an unphased trial, this study offers a unique opportunity to contribute to scientific understanding and potentially gain valuable health insights.

Do I need to stop taking my current medications for the trial?

The trial protocol does not specify whether you need to stop taking your current medications.

What prior data suggests that this protocol is safe?

Research has shown that the Constant Routine Protocol is safe for studying natural body clocks, or circadian rhythms. This protocol involves staying awake in a dimly lit room, moving minimally, and eating snacks at regular intervals. Participants have managed this routine well without major side effects. Researchers closely monitor vital health signs, such as blood pressure and body temperature, to ensure safety. No major safety issues have been reported, indicating it is generally safe for participants. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the Constant Routine Protocol for high blood pressure because it offers a unique way to explore the body’s natural rhythms and their impact on blood pressure. Unlike traditional treatments that typically involve medication to lower blood pressure, this protocol investigates how our body's internal clock, or circadian rhythm, might influence hypertension. By keeping participants in a dimly lit room and monitoring their physiological markers over 30 hours, researchers hope to uncover new insights into how our daily biological cycles affect blood pressure regulation. This could eventually lead to more personalized and effective treatment strategies.

What evidence suggests that the Constant Routine Protocol is effective for high blood pressure?

Research has shown that treating blood pressure in sync with the body's natural daily rhythms can improve control, especially at night. In this trial, participants will undergo the Constant Routine Protocol, which involves staying awake in a dim room while researchers monitor their blood pressure. This method helps researchers understand how the internal body clock affects blood pressure. Evidence suggests that focusing on these natural rhythms might be key to better managing high blood pressure. The trial aims to use the body's own systems to control blood pressure levels effectively. ^{1 3 4 6 7}

Who Is on the Research Team?

Stephen J. Thomas, PhD

Principal Investigator

University of Alabama at Birmingham

Are You a Good Fit for This Trial?

This trial is for participants of the parent grant IDH-MEGA who are interested in understanding how sleep and their body's internal clock affect nighttime blood pressure.

Inclusion Criteria

You are already taking part in the main study called IDH-MEGA.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Constant Routine Protocol

Participants complete a 30-hour constant routine protocol to examine markers of endogenous circadian rhythms, including blood pressure, melatonin, and core body temperature measurements.

30 hours

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after the constant routine protocol

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Constant Routine Protocol

Trial Overview The study is exploring how sleep patterns and circadian rhythms influence high blood pressure at night using a Constant Routine Protocol to monitor changes.

How Is the Trial Designed?

Group I: Constant Routine Protocol Experimental Treatment 1 Intervention

Participants complete a 30-hour constant routine protocol to directly examine markers of endogenous circadian rhythms. In a constant routine protocol, participants remain in a dimly lit room (\<10 lux), in a semi-recumbent posture, remain awake, and consume iso-caloric snacks. Saliva samples are collected and core body temperature and blood pressure are measured.

Who Is Running the Clinical Trial?

University of Alabama at Birmingham

Lead Sponsor

Trials

1,677

Recruited

2,458,000+

Published Research Related to This Trial

The study analyzed blood pressure (BP) rhythms in 378 subjects, revealing that sleep-time hypertensive individuals have lower 24-hour and 12-hour BP rhythm amplitude and integrity compared to awake-time hypertensives, indicating a disorganized circadian rhythm.

This disorganization in BP rhythms among sleep-time hypertensives may be linked to increased cardiovascular risk, highlighting the importance of monitoring BP patterns during both awake and sleep periods.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Blunting of circadian rhythms and increased acrophase variability in sleep-time hypertensive subjects. Perez-Lloret, S., Risk, M., Golombek, DA., et al.[2008]

Blunted blood pressure decline during sleep is linked to a higher risk of cardiovascular events, highlighting the importance of managing blood pressure effectively at night.

Taking blood pressure medications like ACE inhibitors and ARBs in the evening rather than the morning can lead to better control of nighttime blood pressure and improve overall cardiovascular health, suggesting that aligning treatment with the body's natural rhythms (chronotherapy) is beneficial.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Circadian rhythms in blood pressure regulation and optimization of hypertension treatment with ACE inhibitor and ARB medications. Hermida, RC., Ayala, DE., Fernández, JR., et al.[2011]

Using arbitrary times for defining awake and sleep periods in hypertension studies does not significantly change the average blood pressure readings, but it can lead to substantial differences in individual measurements, especially during sleep.

In about 20% to 30% of subjects, the choice of time schedule can alter sleep blood pressure loads by more than 10%, indicating that using actual patient-reported times is crucial for accurate assessment in 24-hour blood pressure monitoring.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effects of actual versus arbitrary awake and sleep times on analyses of 24-h blood pressure. Peixoto Filho, AJ., Mansoor, GA., White, WB.[2009]

In a study of 1720 adults, irregular sleep patterns, specifically a standard deviation of sleep duration greater than 90 minutes over a week, were linked to a higher prevalence of hypertension (HTN) and elevated blood pressure (BP) levels.

Participants without obstructive sleep apnea (OSA) who had significant sleep irregularity were found to have a 48% increased likelihood of having hypertension, highlighting the importance of consistent sleep duration for cardiovascular health.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Sleep irregularity and the association with hypertension and blood pressure levels: the ELSA-Brasil study. Parise, BK., Santos, RB., Mesas, AE., et al.[2023]

In a study analyzing 26,170 ambulatory blood pressure monitoring (ABPM) recordings, it was found that 43% of patients, including those with normal blood pressure, exhibited non-dipping patterns, indicating a potential risk for cardiovascular issues.

Age and body mass index (BMI) were significant factors influencing blood pressure patterns, with older patients and those with a BMI over 30 showing higher rates of non-dipping, which could affect their overall cardiovascular health.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Ambulatory blood pressure monitoring profiles in a cross-sectional analysis of a large database of normotensive and true or suspected hypertensive patients. Araújo, S., Rouxinol-Dias, A., Mesquita-Bastos, J., et al.[2021]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10947115/

Hypertension: Causes and Consequences of Circadian ... In a Constant Routine protocol, individuals maintain continuous wakefulness, physical inactivity, and constant body posture while remaining in constant room ...

2. ahajournals.org ahajournals.org/doi/10.1161/CIRCRESAHA.124.323515

Hypertension: Causes and Consequences of Circadian ... Here, we review the impact of daily rhythms and circadian systems in regulating blood pressure and the onset, progression, and consequences of hypertension.

3. clinicaltrials.gov clinicaltrials.gov/study/NCT05184933

Sleep and Circadian Mechanisms in Hypertension 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 ...

4. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC12302799/

The effect of follow-up on the blood pressure control Conclusions. A moderate increase in follow-up visits may be more effective in reducing hypertension patients' blood pressure than limiting ...

5. withpower.com withpower.com/trial/phase-sleep-2023-742ef

Sleep and Circadian Rhythm Study for High Blood ... Research shows that aligning blood pressure treatment with the body's natural circadian rhythms can improve blood pressure control, especially at night.

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC3086568/

Existence of an Endogenous Circadian Blood Pressure ... During the constant routine protocol there were substantial and significant differences between the timing of the circadian peak in BP (systolic and diastolic) ...

7. ahajournals.org ahajournals.org/doi/10.1161/CIR.0000000000001356

2025 AHA/ACC/AANP/AAPA/ABC/ACCP/ACPM/AGS/AMA/ ... Severe hypertension in nonpregnant individuals, defined as blood pressure >180/120 mm Hg, without evidence of acute target organ damage, should be evaluated and ...