NCT06949644 · Northwestern University
Pupillometry in Delayed Sleep Wake Phase Disorder
What this study is about
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.
View original scientific description
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.
Interventions
COMBINATION_PRODUCT
Light and Citalopram
Participants will receive placebo or citalopram, followed by bright light exposure
Primary outcome measures
Melatonin suppression
Time frame: 8 hours
Saliva melatonin samples will be collected before and after light exposure
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Delayed sleep-wake phase disorder
Exclusion criteria
- 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
Where
- Chicago, Illinois
Collaborators
National Heart, Lung, and Blood Institute (NHLBI)
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jun 8, 2026 · Source of record for eligibility and locations