NCT05483296

Effects of Afternoon and Evening Light on Teenagers' Melatonin Levels, Alertness, Sleepiness and Sleep

Modulating Evening Responses to Light by Afternoon Light Exposure in Adolescents

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 27 (actual)
• Sponsor: University Psychiatric Clinics Basel · Network
• Sex: All
• Age: 14 Years – 17 Years
• Healthy volunteers: Accepted

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.

Conditions

• Healthy
• Teenager
• Healthy Lifestyle

Interventions

Type	Name	Description
OTHER	Dim light condition	During the "Dim" light condition, the four-hour afternoon light exposure at the participants' eye level will be dim (\<5 lx melanopic EDI). In the 4.5-hour evening light exposure, this will constitute a light intensity of \~100 lx melanopic EDI at the participants' eye level.
OTHER	Moderate light condition	During the "Moderate" light condition, the four-hour afternoon light exposure at the participants' eye level will be dim (\~100 lx melanopic EDI). In the 4.5-hour evening light exposure, this will constitute a light intensity of \~100 lx melanopic EDI at the participants' eye level.
OTHER	Bright light condition	During the "Bright" light condition, the four-hour afternoon light exposure at the participants' eye level will be dim (\>1000 lx melanopic EDI). In the 4.5-hour evening light exposure, this will constitute a light intensity of \~100 lx melanopic EDI at the participants' eye level.

Timeline

• Start date: 2022-09-22
• Primary completion: 2023-06-20
• Completion: 2023-06-20
• First posted: 2022-08-02
• Last updated: 2025-03-30

Locations

1 site across 1 country: Switzerland