Carryover effects in melatonin suppression

Carryover effects in melatonin suppression during repeated light exposure in healthy adults: a within-subject controlled trial

Status

Recruiting

Phases

Unknown

Study type

Interventional

Source

ISRCTN

Registry ID

ISRCTN38107747

Enrollment

Registered

2025-06-30

Start date

2025-05-12

Completion date

Unknown

Last updated

2025-09-08

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Chronobiology, melatonin suppression Other

Interventions

This ten-day in-laboratory within-subject study in healthy adults aged 18-40 years examines melatonin suppression and potential carryover effects of repeated evening light exposure (dim light 10 lx, b

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: 1. Age: = 18, = 40 years of age 2. Biological sex: men / women with a natural menstrual cycle / women taking monophasic combined oral contraceptives 3. Good physical health 4. Good mental health 5. Good ocular health 6. Normal color vision 7. Ability to comprehend and communicate in basic Englisch

Exclusion criteria

Exclusion criteria: 1. Biological sex: women taking any other type of hormonal contraception 2. BMI: 30 years 3. Any use of medications 4. Habitual smoking 5. Diagnosis of epilepsy 6. Excessive alcohol use 7. Poor sleep quality 8. Extreme chronotype 9. Shift work in the past 3 months 10. Inter-time zone travel in the past 3 months 11. Currently pregnant and <12 months postpartum 12. Any hormonal imbalances 13. Any drug detected 14. Any alcohol in breath

Design outcomes

Primary

Measure	Time frame
Melatonin concentrations (pg/mL) are determined from saliva samples collected at 30-minute intervals throughout each of the ten evenings in the laboratory.	—

Secondary

Measure	Time frame
1. Subjective sleepiness measured using Karolinska Sleepiness Scale (KSS) scores at 30-minute intervals throughout each of the ten evenings in the laboratory. 2. Reaction time (ms) measured using the psychomotor vigilance test (PVT) at 60-minute intervals throughout each of the ten evenings in the laboratory. 3. Core body temperature measured continuously during each of the ten evenings in the laboratory using indigestible pills by BodyCap. 4. Skin temperature measured continuously during each of the ten evenings in the laboratory using iButtons attached to the ankle (distal) and neck (proximal). 5. Interstitial glucose levels measuring using the continuous glucose monitor during the ambulatory pre-laboratory, laboratory and post-laboratory period.	—

Measure

Time frame

1. Subjective sleepiness measured using Karolinska Sleepiness Scale (KSS) scores at 30-minute intervals throughout each of the ten evenings in the laboratory. 2. Reaction time (ms) measured using the psychomotor vigilance test (PVT) at 60-minute intervals throughout each of the ten evenings in the laboratory. 3. Core body temperature measured continuously during each of the ten evenings in the laboratory using indigestible pills by BodyCap. 4. Skin temperature measured continuously during each of the ten evenings in the laboratory using iButtons attached to the ankle (distal) and neck (proximal). 5. Interstitial glucose levels measuring using the continuous glucose monitor during the ambulatory pre-laboratory, laboratory and post-laboratory period.

—

Countries

Germany

Contacts

Public ContactLetizia Wörrlein

letizia.woerrlein@tum.de+49 (0)89 289 - 24544

Outcome results

None listed

Source: ISRCTN (via WHO ICTRP) · Data processed: Feb 4, 2026