Effects of Afternoon and Evening Light on Teenagers' Melatonin Levels, Alertness, Sleepiness and Sleep
- Conditions
- HealthyHealthy LifestyleTeenager
- Interventions
- Other: Low light conditionOther: Moderate light conditionOther: High light condition
- Registration Number
- NCT05483296
- Lead Sponsor
- University Psychiatric Clinics Basel
- Brief Summary
Many teenagers are familiar with this: on school days, they have to get up early; during the day, they hardly get any light exposure; in the evening, they go to bed late - and are then tired at school the next day! Around the world, teenagers are sleep deprived, with studies suggesting that almost half (\~45%) suffer from inadequate sleep. Previous investigations have shown that people's sleep-wake rhythm is related to the light conditions that they are exposed to during the day and at night. However, little is known about how different light levels in the afternoon can modulate teenagers' sleep and their bodily responses to light in the late evening. Therefore, the investigators aim to study which lighting conditions have a favourable effect on these aspects and how the potentially harmful effects of light at night can be prevented.
- Detailed Description
Light exposure during adolescence seems to be the critical component of a vicious circle. Due to the maturation of sleep-wake regulatory systems in combination with progressively ill-timed exposure to light and early school start times, teenagers suffer from the accumulation of sleep depth during school days. Therefore, the proposed study investigates whether the physiological and alerting effects of late evening light exposure in adolescents depend on the intensity of light exposure in the preceding afternoon (primary endpoint: evening melatonin concentration).
The investigators aim to describe dose-response relationships, where the "dose" is the preceding (real-world applicable) afternoon light intensity (\< 10 lx, \~100 lx, or \>1000 lx EDI, 4-hour duration), and the "responses" are the adolescents' physiological and alerting responses to evening light exposure (\~100 lx melanopic EDI, 4.5-hour duration). By this route, the researchers can explore whether increasing afternoon light exposure is a feasible target for ameliorating the detrimental effects of artificial light at night and promoting healthier sleep-wake regulation during adolescence.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 27
- Healthy
- Capable of judgment
- Normal BMI (Age-related Body-Mass-Index Percentile > P3 & < P97; approx. corresponding to 28.5 ≥ BMI ≤ 16)
- Signed consent form of participants
- Signed consent form of a legal representative
- Pregnancy or breastfeeding (only female)
- Current participation in other clinical trials
- Extreme chronotype (Extreme early or late chronotype/mid sleep time: mid-sleep time < 1:00 / > 7:00)
- Extremely short or long sleep durations during school- or work days (< 6 hours > 11 hours)
- Sleep disorders
- High myopia (< -6 diopters)
- High hyperopia (> +6 diopters)
- Non-normal best-corrected visual acuity (BCVA < 0.5 [20/40])
- General health concerns or disorders, including heart and cardiovascular, neurological, nephrological, endocrinological, and psychiatric conditions
- Ophthalmological or optometric conditions
- Medication impacting visual, neuroendocrine, sleep, and circadian physiology
- Drug and alcohol use (urinary drug screening & breathalyzer test)
- Non-compliance with sleep-wake times: >1 deviation from ±60 minute window sleep and wake-up time
- Non-compliance with caffeine intake (> 1 times caffeine intake)
- Transmeridian travel (>2 time zones) <1 month prior to the first session of the study
- shift work <3 months prior to the beginning of the study
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- CROSSOVER
- Arm && Interventions
Group Intervention Description Crossover sequence 2: Dim, High, Moderate High light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \<10 lx. In the second experimental session, they receive an intensity of \>1000 lx, and in the third experimental session, they receive an intensity of \~100 lx. Crossover sequence 5: High, Moderate, Dim High light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \>1000 lx. In the second experimental session, they receive an intensity of \~100 lx, and in the third experimental session, they receive an intensity of \<10 lx. Crossover sequence 5: High, Dim, Moderate Low light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \>1000 lx. In the second experimental session, they receive an intensity of \<10 lx, and in the third experimental session, they receive an intensity of \~100 lx. Crossover sequence 3: Moderate, Dim, High High light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \~100 lx. In the second experimental session, they receive an intensity of \<10 lx, and in the third experimental session, they receive an intensity of \>1000 lx. Crossover sequence 5: High, Dim, Moderate Moderate light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \>1000 lx. In the second experimental session, they receive an intensity of \<10 lx, and in the third experimental session, they receive an intensity of \~100 lx. Crossover sequence 1: Dim, Moderate, High Low light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \<10 lx. In the second experimental session, they receive an intensity of \~100 lx, and in the third experimental session, they receive an intensity of \>1000 lx. Crossover sequence 5: High, Moderate, Dim Low light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \>1000 lx. In the second experimental session, they receive an intensity of \~100 lx, and in the third experimental session, they receive an intensity of \<10 lx. Crossover sequence 5: High, Moderate, Dim Moderate light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \>1000 lx. In the second experimental session, they receive an intensity of \~100 lx, and in the third experimental session, they receive an intensity of \<10 lx. Crossover sequence 1: Dim, Moderate, High Moderate light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \<10 lx. In the second experimental session, they receive an intensity of \~100 lx, and in the third experimental session, they receive an intensity of \>1000 lx. Crossover sequence 2: Dim, High, Moderate Low light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \<10 lx. In the second experimental session, they receive an intensity of \>1000 lx, and in the third experimental session, they receive an intensity of \~100 lx. Crossover sequence 2: Dim, High, Moderate Moderate light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \<10 lx. In the second experimental session, they receive an intensity of \>1000 lx, and in the third experimental session, they receive an intensity of \~100 lx. Crossover sequence 3: Moderate, Dim, High Moderate light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \~100 lx. In the second experimental session, they receive an intensity of \<10 lx, and in the third experimental session, they receive an intensity of \>1000 lx. Crossover sequence 4: Moderate, High, Dim Low light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \~100 lx. In the second experimental session, they receive an intensity of \>1000 lx, and in the third experimental session, they receive an intensity of \<10 lx. Crossover sequence 1: Dim, Moderate, High High light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \<10 lx. In the second experimental session, they receive an intensity of \~100 lx, and in the third experimental session, they receive an intensity of \>1000 lx. Crossover sequence 3: Moderate, Dim, High Low light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \~100 lx. In the second experimental session, they receive an intensity of \<10 lx, and in the third experimental session, they receive an intensity of \>1000 lx. Crossover sequence 4: Moderate, High, Dim Moderate light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \~100 lx. In the second experimental session, they receive an intensity of \>1000 lx, and in the third experimental session, they receive an intensity of \<10 lx. Crossover sequence 4: Moderate, High, Dim High light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \~100 lx. In the second experimental session, they receive an intensity of \>1000 lx, and in the third experimental session, they receive an intensity of \<10 lx. Crossover sequence 5: High, Dim, Moderate High light condition All participants will go through all three light conditions in the three experiment sessions: They will receive white fluorescent overhead light (given in melanopic EDI at eye level) as the 3h afternoon light intervention. In the first experimental session, they receive an intensity of \>1000 lx. In the second experimental session, they receive an intensity of \<10 lx, and in the third experimental session, they receive an intensity of \~100 lx.
- Primary Outcome Measures
Name Time Method Salivary melatonin Through study completion, estimated 1.5 years (within 3 weeks for each participant) Salivary melatonin. Saliva samples (\>1 mL) will be taken from the participants every 30 Minutes using Salivettes. The Salivettes will be centrifuged, the cotton part removed and immediately frozen at -20°C. At a later point, melatonin \[in pg\] will be determined in these samples by double-antibody radioimmunoassay (RIA). To quantify melatonin suppression, the analytic team will calculate the area under the curve (AUC) for each laboratory condition.
- Secondary Outcome Measures
Name Time Method Sleep Onset Latency (PSG-derived) Through study completion, estimated 1.5 years (within 3 weeks for each participant) The investigators will operationalise Sleep Onset Latency according to the American Academy of Sleep Medicine (AASM) Manual for the Scoring of Sleep and Associated Events (time interval from lights out to the first PSG-derived sleep epoch in minutes).
Subjective sleepiness Through study completion, estimated 1.5 years (within 3 weeks for each participant) The investigators will assess subjective sleepiness using the single-item 9-point Karolinska Sleepiness Scale (KSS) - a well-validated, highly sensitive subjective Likert-type measurement scale for subjective sleepiness.
Scores range from 1 to 9 with higher values on the scale corresponding to higher sleepiness.Sleep stages (PSG-derived) Through study completion, estimated 1.5 years (within 3 weeks for each participant) The investigators will score the PSG-derived sleep stages and arousals according to the American Academy of Sleep Medicine (AASM) Manual for the Scoring of Sleep and Associated Events.
Melanopsin sensitivity (pupillary light response) Through study completion, estimated 1.5 years (within 3 weeks for each participant) The investigators will measure changes in the pupil area using silent substitution pupillography and examine the differences between melanopsin response amplitude before the afternoon light condition (pre-light treatment) and the melanopsin response amplitude after the afternoon light condition (post-light treatment).
Slow wave activity (PSG-derived) Through study completion, estimated 1.5 years (within 3 weeks for each participant) The investigators will examine slow-wave activity (SWA; delta power density between 0.5 and 4.5 Hz) during the first sleep cycle. EEG slow-wave activity (SWA) (i.e., delta power density between 0.5 and 4.5 Hz) will be calculated as an indicator of sleep propensity across the night within each non-rapid eye movement NREM part of a sleep cycle.
Objective sleepiness 2 Through study completion, estimated 1.5 years (within 3 weeks for each participant) The volunteers will perform a Karolinska Drowsiness Test (KDT) three times during scheduled wakefulness. During the KDT, participants fixate on a point on the wall from a one-meter distance for five minutes (eyes open). These sessions will provide EEG data with relatively few artefacts. As the second indicator for objective sleepiness, electro-oculogram-derived (EOG-derived) slow-eye movements will be calculated.
Vigilant attention Through study completion, estimated 1.5 years (within 3 weeks for each participant) Objective alertness will be measured using a modified auditory Psychomotor Vigilance Test (aPVT). After a response, the next tone will be played randomly after 2-10 s. The reaction time data will focus on mean 1/reaction time (mean 1/RT), the most sensitive measure for a slight deviation in sleep pressure. Mean 1/RT will be calculated after the removal of false starts and lapses.
Skin temperature Through study completion, estimated 1.5 years (within 3 weeks for each participant) Skin temperature will be continuously monitored with six surface temperature thermocouples placed on proximal and distal regions of the body surface. Skin temperatures (distal \& proximal) and the distal-proximal skin temperature gradient (DPG) will be calculated.
Objective sleepiness 1 Through study completion, estimated 1.5 years (within 3 weeks for each participant) The volunteers will perform a Karolinska Drowsiness Test (KDT) three times during scheduled wakefulness. During the KDT, participants fixate on a point on the wall from a one-meter distance for five minutes (eyes open). These sessions will provide EEG data with relatively few artefacts. As the first indicator for objective sleepiness, EEG-derived alpha/theta ratio will be calculated.
Trial Locations
- Locations (1)
Psychiatric University Clinics (UPK), Centre for Chronobiology
🇨🇭Basel, canton of Basel city, Switzerland