Pupillometry in Delayed Sleep Wake Phase Disorder

April 7, 2026 updated by: Sabra Abbott, Northwestern University

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.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

220

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: DSWPD
Placebo or Citalopram followed by bright light (all participants will receive both interventions in random order).
Combination product: Light and Citalopram
Participants will receive placebo or citalopram, followed by bright light exposure

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Melatonin suppression
Time Frame: 8 hours
Saliva melatonin samples will be collected before and after light exposure
8 hours

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Northwestern University

Collaborators

National Heart, Lung, and Blood Institute (NHLBI)

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

September 1, 2025

Primary Completion (Estimated)

February 28, 2029

Study Completion (Estimated)

July 31, 2029

Study Registration Dates

First Submitted

April 22, 2025

First Submitted That Met QC Criteria

April 22, 2025

First Posted (Actual)

April 29, 2025

Study Record Updates

Last Update Posted (Actual)

April 8, 2026

Last Update Submitted That Met QC Criteria

April 7, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • STU00221304
  • R01HL174661 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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