Recruiting

Observational StudyImpact of Sex and Age on Non-visual Light Input That Affects Sleep and Circadian Rhythms

Sponsor:

Massachusetts General Hospital

Code:

NCT05829044

Conditions

Normal Physiology

Eligibility Criteria

Sex: All

Age: 18 - 70+

Healthy Volunteers: Accepted

Interventions

Pupillometry

Light box exposure

Study Details

Brief summary:

The goal of this clinical trial is to learn how the pupil responds to different light stimuli and how that relates to sleep and daily rhythms in healthy people of different ages.

The main questions it aims to answer are:

Does the eye's pupil response to light stimuli differ by the sex and age of the participant?
Is the eye's pupil response to light stimuli related to each participant's sleep timing, their body clock timing, and their hormone responses to light.

Participants will have a special eye exam and complete questionnaires before starting the study to see if they can participate. If they can participate, they will wear a special watch that monitors their activity and light levels for one week. Then they will live in a research room at the Mass General Hospital for 3 days/2 nights during which we will test their pupil response to light, their body clock timing, and their hormone responses to light.

Conditions

Normal Physiology

Study ID

NCT05829044

Start date

Dec 1, 2023

Status verified date

Jul, 2026

Completion date

Jun 30, 2027

Anticipated

Primary completion date

Jun 30, 2027

Anticipated

Eligibility Criteria

Sex: All

Age: 18 - 70+

Healthy Volunteers: Accepted

Inclusion Criteria:

(i) 18-85 years old.
(ii) Habitual sleep onset 10 pm- 1 am (healthy controls only);
(iii) Habitual wake onset 5:30 am- 8:30 am (healthy controls only);
(iv) vision correctable to 20/30;
(v) stable medically.
(vi) ability to speak, understand, and read English at a high school level

Exclusion Criteria:

(i) Color blind by Ishihara Color Blindness Test;
(ii) any history of eye trauma, surgery or abnormality (e.g., retinopathy, glaucoma, cataracts, amblyopia, macular degeneration, congenital color vision deficiencies, or any type of blindness) besides correctable vision abnormalities (e.g., with glasses); any abnormalities on clinical eye exam (e.g., neuritis, Neuromyelitis optica, treated or untreated glaucoma) such that the ophthalmologist recommends the participant not be studied; Limited cataracts (e.g., Lens Opacities Classification (LOCS) III grade <2) will be allowed and documented during the eye exam. Eye drops that affect pupil size or contractility (e.g. mydriatics, miotics); drops to treat glaucoma (e.g., pilocarpine, brimonidine, other drops like artificial tear drops, or anti-inflammatory drops would not be exclusionary)
(iii) current or history of neurologic or psychiatric disease including autonomic function disorder or migraines; psychiatric disorder requiring medications in a first degree relative (healthy controls only); limited-duration counseling without prescription medications will not be exclusionary; (iv) current or history of circadian rhythm sleep-wake disorder (healthy controls only);
(v) prescription or non-prescription drugs affecting the pupil (e.g., affecting autonomic function), sleep, melatonin (e.g., lithium, alpha- and beta-adrenergic antagonists), and/or circadian rhythms (e.g., beta blockers, non-steroidal anti-inflammatory drugs, tricyclics);
(vi) Other disorders that can affect or may be affected by intrinsically photosensitive Retinal Ganglion Cell (ipRGC) function, including diabetes mellitus, multiple sclerosis, Parkinson's disease, seasonal affective disorder;
(vii) shift- or night-work in past three months; history of night work in preceding 3 year period
(viii) crossing more than 2 time zones in past three months;
(ix) presence of depression as assessed by a Beck Depression Inventory (BDI) score >14.
(x) pregnant or less than 6 weeks post-partum or breast-feeding

Study Design

Enrollment

48 participants

Anticipated

Intervention Model

Single group

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: Testing non-visual light impacts on pupil response, circadian timing, and hormones

1. Pupillometry on day 1 in afternoon and evening and on day 2 in morning and evening. Participants will be randomized to one of 8 different light stimuli within the pupillometry
2. Red light exposure on night 1 to determine circadian timing
3. Blue/green light exposure on night 2 to compare hormone response during blue/green light to that during red light on night 1

Interventions

Pupillometry

Pupillometer measurement of pupil size in response to different light stimuli

Light box exposure

Using a light box to produce different wavelengths and intensities of light. Exposure to red light on Night 1 and blue/green light on Night 2 to determine circadian timing and suppression of hormone (melatonin)

Primary outcome measure

Pupil size [ Time Frame: During pupillometry testing on Day 1 afternoon, Day 1 evening, Day 2 morning, Day 2 evening ]
Melatonin levels for circadian timing assessment [ Time Frame: Night 1 ]
Melatonin levels for hormone response [ Time Frame: Night 1 and Night 2 ]

Central Contacts and Locations

Central contacts

Elizabeth B Klerman, MD PhD

617-643-2424 ebklerman@mgh.harvard.edu

Locations

Massachusetts General Hospital

Recruiting

Boston, Massachusetts, United States, 02114

Contacts

Elizabeth Klerman, MD PhD

857-507-0765 mgh_pulsar_study@mgb.org

More Information

Sponsor

Massachusetts General Hospital

Last update posted

Jul 13, 2026

Last verified

Jul, 2026

Keywords

eye pupil response
circadian rhythms
light
melatonin

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by Massachusetts General Hospital on 2026-07-13.