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Understanding Light's Impact on Sleep and Body Rhythms

This study aims to understand how different types of light affect your pupils, sleep patterns, and natural body clock (circadian rhythms). Researchers will use a pupillometer to measure your pupil size and a light box to expose you to red, blue, and green light. They will also measure your melatonin levels, a hormone that helps regulate sleep, to see how light influences your body's timing. The study is looking for 48 healthy volunteers, aged 18 to 85, who have regular sleep schedules and good vision. The main goal is to see if age and sex influence how your eyes respond to light and how this relates to your sleep and hormone responses.

Study design
This interventional study plans to enroll 48 healthy participants of all genders, aged 18 to 85 years old.
What's involved
You will have an eye exam and complete questionnaires. If eligible, you will wear a special watch for one week and undergo pupillometry testing and light box exposure on specific days and nights.
Compensation
Not stated in the trial record.
Follow-up
Melatonin levels will be measured on Night 1 and Night 2, and pupil size will be measured on Day 1 and Day 2, indicating a short follow-up period.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT05829044

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

Recruiting
NAAges 18–85InterventionalBasic science
Massachusetts General Hospital
~48 participants
Updated 2026-07-13 on ClinicalTrials.gov
What's tested:PupillometryLight box exposure

At a glance

Recruiting sites
1 of 1 listed site is recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Pupil size
Measured over During pupillometry testing on Day 1 afternoon, Day 1 evening, Day 2 morning, Day 2 evening
+2 more outcomes measured

Conditions

Normal Physiology

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Healthy Volunteers

NCT05829044

Where you'd take part

This study runs at 1 site. They're the same protocol — you choose where, and that choice sets who your contact draft is addressed to.

  • Massachusetts General Hospital

    Boston, Massachusettsstudy coordinator listed

    Recruiting

Sites open and close at different times, so the status above is per site — it can differ from the study's overall status.

Study leadership

  • Elizabeth B Klerman, MD PhD · PRINCIPAL_INVESTIGATOR · Massachusetts General Hospital

Who to contact

Elizabeth B Klerman, MD PhD
[email protected]
617-643-2424
Email the study team

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Eligibility criteria

Inclusion

(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

(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

What this trial measures

  • Pupil sizeDuring pupillometry testing on Day 1 afternoon, Day 1 evening, Day 2 morning, Day 2 evening

    Pupil size as measured by pupillometry

  • Melatonin levels for circadian timing assessmentNight 1

    Melatonin levels from saliva collection during Night 1 light box red light exposure

  • Melatonin levels for hormone responseNight 1 and Night 2

    Melatonin levels from saliva collection during Night 2 light box blue/green light exposure compared to those during Night 1 light box red light exposure