Pupil light-response testing for delayed sleep-wake phase disorder
Official title: Pupillometry in DSWPD Type 1 and Type 2
Run by Northwestern University · NCT06949644 · Data updated 2026-11-12
This study tests whether people with delayed sleep-wake phase disorder have different pupil responses to light and whether a single dose of citalopram increases light-induced melatonin suppression.
Quick facts
| Study type | Interventional |
|---|---|
| Ages | 16 Years and up |
| Sex | All |
| Enrollment | 220 (estimated) |
| Sponsor | Northwestern University Academic / other |
| Locations | 1 site (Chicago, Illinois) |
| Status | Recruiting |
| Started | September 1, 2025 |
| Main results expected | July 31, 2029 |
| Study ends | August 31, 2029 |
| Registry record updated | June 8, 2026 |
| Trial ID | NCT06949644 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Ideal candidates are people diagnosed with delayed sleep-wake phase disorder who have stable medical and psychiatric conditions, no eye disease or eye surgery history, are not using medications that alter pupil size, are not shift workers, and consume less than 400 mg of caffeine per day.
✕Probably not a fit
People with eye disease or prior eye surgery, those taking drugs that change pupil diameter, shift workers or those with unstable medical/psychiatric conditions are unlikely to benefit or be eligible.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
Participants first complete at-home activity monitoring and melatonin timing tests to determine their circadian phase. They then undergo eye testing to measure pupil responses to different light stimuli. A subset returns for two inpatient sessions with bright light exposure and melatonin sampling, receiving placebo in one session and a single dose of citalopram in the other. The design compares pupil and melatonin responses within individuals to see if serotonin modulation changes the circadian response to light.
Why it matters
Potential benefit: If successful, the work could clarify a biological mechanism of delayed sleep-wake phase disorder and point to new ways to shift circadian timing with light or medication.
How similar studies have gone: Previous work has characterized pupil light responses and melatonin suppression, but using an acute dose of citalopram to modify light-induced melatonin suppression is relatively novel and prior evidence is mixed.
Who can join: the full rules
Show full inclusion / exclusion criteria
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 it's running
-
Northwestern University
Chicago, Illinois, United States Recruiting
Study contacts
- Study coordinator: Sabra Abbott, MD, PhD
- Email: sabra.abbott@northwestern.edu
- Phone: 312-695-7950
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.