Delayed Sleep-Wake Phase DisorderNCT06949644
Pupillometry in Delayed Sleep Wake Phase Disorder
A study testing Light and Citalopram in people with Delayed Sleep-Wake Phase Disorder, run by Northwestern University at 1 site in United States.
Trial summary
The goal of this observational study is to characterize the pupil light response in patients with delayed sleep-wake phase disorder. A subset of participants will take part in a clinical trial to determine if increasing serotonin can alter the circadian response to light. Read more about this study
- Who is it for?
- Ages 16 years and older
- Conditions the study is for
- Delayed Sleep-Wake Phase Disorder
- What is being tested?
- Light and Citalopram
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 220 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Sep 2025to 31 Aug 2029
- 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 16 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Delayed sleep-wake phase disorder
Who cannot join
- Use of medications known to alter pupil diameter
- History of eye disease or eye surgery
- Unstable medical or psychiatric condition
- Shift work or self imposed irregular sleep schedules
- Caffeine consumption >400mg/day
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, 1 recruiting
- Recruiting
Northwestern University
Chicago, Illinois, 60611
Research Assistant, 312-908-1024, sleeplab@northwestern.edu
About this study
Official title: Pupillometry in DSWPD Type 1 and Type 2
The goal of this observational study is to characterize the pupil light response in patients with delayed sleep-wake phase disorder. A subset of participants will take part in a clinical trial to determine if increasing serotonin can alter the circadian response to light. The main questions it aims to answer is:
Are there differences in the light response in patients with delayed sleep-wake phase disorder? Does citalopram increase melatonin suppression in patients with delayed sleep-wake phase disorder?
Participants will complete activity and melatonin testing at home to determine their circadian timing. This will be followed by an eye test looking at the pupil response to different light stimuli. A subset of participants will complete two inpatient admissions where melatonin levels will be sampled and they will be exposed to a bright light. During one round of testing they will receive a placebo and in the other round of testing they will take a single dose of citalopram, a selective serotonin reuptake inhibitor.
- Conditions
- Delayed Sleep-Wake Phase Disorder
- Being tested
- Light and Citalopram
- Medical subject headings
- Sleep Disorders, Circadian Rhythm
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Light and CitalopramCombination product
Participants will receive placebo or citalopram, followed by bright light exposure
| Study group | Role | What they receive |
|---|---|---|
| DSWPD | Experimental | Placebo or Citalopram followed by bright light (all participants will receive both interventions in random order). Receives: Combination Product: Light and Citalopram |
What is being measured
The primary outcome is the main question the study is designed to answer.
Melatonin suppression
Saliva melatonin samples will be collected before and after light exposure
Measured: 8 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Apr 2025
- Study start1 Sep 2025
- Primary completion31 Jul 2029 (estimated)
- Study completion31 Aug 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Delayed Sleep-Wake Phase DisorderStudies of the same condition, open and under way.
- More trials run by Northwestern UniversityThe 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
- Diagnosis
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 220 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Northwestern University
- Sponsor type
- University, hospital or other
- Collaborators
- National Heart, Lung, and Blood Institute (NHLBI)
- Responsible party
- Principal investigator, Sabra Abbott, Northwestern University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06949644
- Sponsor's protocol ID
- STU00221304
- Other IDs
- R01HL174661
- Status last verified
- Jun 2026
- First submitted
- 22 Apr 2025
- Last updated
- 8 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 8 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Pupillometry in DSWPD Type 1 and Type 2
- ClinicalTrials.gov ID
- NCT06949644
- Acronym / sponsor ID
- STU00221304
- Conditions
- Delayed Sleep-Wake Phase Disorder
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 220 participants (estimated)
- Lead sponsor
- Northwestern UniversityUniversity, hospital or other
- Collaborators
- National Heart, Lung, and Blood Institute (NHLBI)
- Study start
- 1 Sep 2025 (actual)
- Primary completion
- 31 Jul 2029 (estimated)
- Study completion
- 31 Aug 2029 (estimated)
- First posted
- 29 Apr 2025 (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.
The goal of this observational study is to characterize the pupil light response in patients with delayed sleep-wake phase disorder. A subset of participants will take part in a clinical trial to determine if increasing serotonin can alter the circadian response to light. The main questions it aims to answer is:
Are there differences in the light response in patients with delayed sleep-wake phase disorder? Does citalopram increase melatonin suppression in patients with delayed sleep-wake phase disorder?
Participants will complete activity and melatonin testing at home to determine their circadian timing. This will be followed by an eye test looking at the pupil response to different light stimuli. A subset of participants will complete two inpatient admissions where melatonin levels will be sampled and they will be exposed to a bright light. During one round of testing they will receive a placebo and in the other round of testing they will take a single dose of citalopram, a selective serotonin reuptake inhibitor.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| DSWPD | Experimental | Combination Product: Light and CitalopramPlacebo or Citalopram followed by bright light (all participants will receive both interventions in random order). |
Who may qualify
- Ages
- 16 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (1 listed)
- Delayed sleep-wake phase disorder
Key exclusion criteria (5 listed)
- Use of medications known to alter pupil diameter
- History of eye disease or eye surgery
- Unstable medical or psychiatric condition
- Shift work or self imposed irregular sleep schedules
- Caffeine consumption >400mg/day
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 |
|---|---|---|
| Light and CitalopramParticipants will receive placebo or citalopram, followed by bright light exposure | Combination product | DSWPD |
Primary outcome
Melatonin suppression
Time frame: 8 hours
Saliva melatonin samples will be collected before and after light exposure
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 8 Jun 2026.
- Individual participant dataSharing planned: Undecided
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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.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Light and Citalopram in people with Delayed Sleep-Wake Phase Disorder, run by Northwestern University 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 5 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: looking for participants now, as of the sponsor's last update on 8 Jun 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?
Contact Sabra Abbott, MD, PhD (312-695-7950, sabra.abbott@northwestern.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Melatonin suppression (time frame: 8 hours). 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 8 Jun 2026.