SleepSCN-BPNCT05656768
Sleep and Circadian Contributions to Nighttime Blood Pressure
A study testing Constant Routine Protocol in people with Sleep and Circadian Rhythm, run by University of Alabama at Birmingham at 1 site in United States.
Trial summary
Broadly, this study (SCN-BP) seeks to examine sleep and circadian factors that contribute to blood pressure levels at night. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Sleep, Circadian Rhythm, Blood Pressure
- What is being tested?
- Constant Routine Protocol
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 1,427 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Jun 2023to 30 Dec 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Participant in the parent grant (IDH-MEGA)
Who cannot join
- -
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site
University of Alabama at Birmingham
Birmingham, Alabama, 35294-0017
About this study
Broadly, this study (SCN-BP) seeks to examine sleep and circadian factors that contribute to blood pressure levels at night.
Read the detailed description
SCN-BP is imbedded in a parent grant titled "Improving the Detection of Hypertension (IDH-MEGA)" and examines a variety of sleep (e.g., sleep duration, timing, and the presence of sleep disorder) and circadian factors in Aims 1 and 2. In Aim 3, the investigators will conduct a 30-hour constant routine protocol to directly examine endogenous circadian and blood pressure rhythms. Aims 1 and 2 are purely observation. The study design design described below pertains the intervention piece of this study (Aim 3).
- Conditions
- Sleep, Circadian Rhythm, Blood Pressure, Hypertension
- Being tested
- Constant Routine Protocol
- Keywords
- sleep, circadian rhythm, circadian misalignment, nocturnal hypertension, non-dipping blood pressure
- Medical subject headings
- Hypertension
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Constant Routine ProtocolOther
A constant routine protocol is used to directly examine markers of circadian rhythmicity (e.g., melatonin and core body temperature). A constant routine protocol requires an individual to remain in a dimly lit room, in a constant semi-recumbent posture, and remain awake for more than 24 hours. It is one of two gold-standard research protocols for examining circadian rhythms in humans.
| Study group | Role | What they receive |
|---|---|---|
| Constant Routine Protocol | Experimental | 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. Receives: Other: Constant Routine Protocol |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Melatonin
Melatonin levels obtained from saliva samples
Measured: Hourly samples obtained over 30 hours
Change in Core body temperature
Core body temperature
Measured: Continuous measurements over 30 hours
Secondary outcomes (1)
Change in Blood pressure
Systolic and diastolic blood pressure obtained using an ambulatory blood pressure monitor
Measured: Measurements obtained every 30 minutes over 30 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Dec 2022
- Study start1 Jun 2023
- Primary completion30 Dec 2028 (estimated)
- Study completion30 Dec 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for SleepStudies of the same condition, open and under way.
- More trials run by University of Alabama at BirminghamThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 1,427 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Alabama at Birmingham
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Stephen Justin Thomas, PhD, University of Alabama at Birmingham
- Investigators
- Stephen J Thomas, PhD, Principal investigator, University of Alabama at Birmingham
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05656768
- Sponsor's protocol ID
- IRB-300010042
- Acronym
- SCN-BP
- Status last verified
- Jan 2026
- First submitted
- 18 Nov 2022
- Last updated
- 29 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 29 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Sleep and Circadian Contributions to Nighttime Blood Pressure
- ClinicalTrials.gov ID
- NCT05656768
- Acronym / sponsor ID
- SCN-BP / IRB-300010042
- Conditions
- Sleep, Circadian Rhythm, Blood Pressure, Hypertension
- Keywords
- sleep, circadian rhythm, circadian misalignment, nocturnal hypertension, non-dipping blood pressure
- Study type
- Interventional
- Recruitment status
- Enrolling by invitation
- Enrolment
- 1,427 participants (estimated)
- Lead sponsor
- University of Alabama at BirminghamUniversity, hospital or other
- Study start
- 1 Jun 2023 (actual)
- Primary completion
- 30 Dec 2028 (estimated)
- Study completion
- 30 Dec 2028 (estimated)
- First posted
- 19 Dec 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Broadly, this study (SCN-BP) seeks to examine sleep and circadian factors that contribute to blood pressure levels at night.
Detailed description
SCN-BP is imbedded in a parent grant titled "Improving the Detection of Hypertension (IDH-MEGA)" and examines a variety of sleep (e.g., sleep duration, timing, and the presence of sleep disorder) and circadian factors in Aims 1 and 2. In Aim 3, the investigators will conduct a 30-hour constant routine protocol to directly examine endogenous circadian and blood pressure rhythms. Aims 1 and 2 are purely observation. The study design design described below pertains the intervention piece of this study (Aim 3).
Study design
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Constant Routine Protocol | Experimental | Other: Constant Routine ProtocolParticipants 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 may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- Participant in the parent grant (IDH-MEGA)
Key exclusion criteria (1 listed)
- -
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Constant Routine ProtocolA constant routine protocol is used to directly examine markers of circadian rhythmicity (e.g., melatonin and core body temperature). A constant routine protocol requires an individual to remain in a dimly lit room, in a constant semi-recumbent posture, and remain awake for more than 24 hours. It is one of two gold-standard research protocols for examining circadian rhythms in humans. | Other | Constant Routine Protocol |
Primary outcome
Change in Melatonin
Time frame: Hourly samples obtained over 30 hours
Melatonin levels obtained from saliva samples
Change in Core body temperature
Time frame: Continuous measurements over 30 hours
Core body temperature
1 secondary outcome
Change in Blood pressure
Time frame: Measurements obtained every 30 minutes over 30 hours
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Jan 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Stephen J Thomas, PhD principal investigator
University of Alabama at Birmingham
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Constant Routine Protocol in people with Sleep and Circadian Rhythm, run by University of Alabama at Birmingham at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: enrolling by invitation, as of the sponsor's last update on 29 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Melatonin (time frame: Hourly samples obtained over 30 hours). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Jan 2026.