An interventional study of Light and Citalopram in Delayed Sleep-Wake Phase Disorder, sponsored by Northwestern University. Recruiting at 1 site in United States. Open to participants aged 16 Years and older. Per ClinicalTrials.gov, last updated 2026-06-08.
Sponsored by Northwestern University · Not applicable, Interventional, and Diagnostic
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.
135 studies on the registry are indexed under Sleep Disorders, Circadian Rhythm; 25 are open to participants now.
This study's planned enrollment of 220 is above the median of 59 across 102 interventional studies indexed under Sleep Disorders, Circadian Rhythm.
Browse Sleep Disorders, Circadian Rhythm studies →Northwestern University is the lead sponsor of 1,423 studies on the registry; 198 are open to participants now.
Of its 105 completed or terminated interventional studies of FDA-regulated products, 78 (74%) have results posted.
Counted across the registry records on this site, refreshed daily.
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Exclusion Criteria:
Placebo or Citalopram followed by bright light (all participants will receive both interventions in random order).
Combination Product: Light and Citalopram
Drug pages: Tumor Necrosis Factor Ligand Superfamily Member 14 · Citalopram
Participants will receive placebo or citalopram, followed by bright light exposure
Melatonin suppression
Saliva melatonin samples will be collected before and after light exposure
Time frame: 8 hours
Plan to share: Undecided
No publications or documents are linked to this record.
Started Sep 2025 (actual). Primary completion is estimated for Jul 2029, 46 months after the start.
Of 39 non-industry interventional studies with no phase under Sleep Disorders, Circadian Rhythm, half reached primary completion within 28 months of starting (the median), counting those still running; a quarter within 8 and three quarters within 51. This study's planned 46 months is above that.
Counting every sponsor, half of 42 studies reached it within 28 months; a quarter within 8 and three quarters within 46.
How these figures are worked out, and which studies are left out of them.
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Studies of the drugs tested here: Tumor Necrosis Factor Ligand Superfamily Member 14 · Citalopram
Sleep Disorders, Circadian Rhythm →