NCT05423002

Effect of Different Color Lights on the Internal Clock and Alertness in Humans

Mechanisms of Cone Photoreceptors Contribution on Human Neuroendocrine Physiology and Pupillary Light Responses

• Status: Unknown
• Phase: N/A
• Study type: Interventional
• Enrollment: 68 (estimated)
• Sponsor: University of Basel · Academic / Other
• Sex: All
• Age: 18 Years – 35 Years
• Healthy volunteers: Accepted

Summary

The main aim of this study is to investigate the effects of cone-modulated light emitted from a visual display on human circadian physiology and cognitive performance in the evening.

Detailed description

The investigators will generate single/multiple cone-isolating contrasts with equivalent stimuli for other cones and melanopsin photoreceptors. The investigators will assess melatonin suppression under three different light scenarios generated using the method of silent substitution by tuning the spectral composition of the light primaries (e.g. LEDs) such that a single target photoreceptor class is maximally stimulated compared to an equal stimulation of the remaining photoreceptors. Additionally, The investigators will examine pupil response, subjective sleepiness, psychomotor vigilance, visual comfort, and skin temperature under three different light scenarios. This allows for new insights into the lights' cone-contribution mechanism to neuroendocrine physiology in the human retina.

Conditions

• Light Flashing

Interventions

Type	Name	Description
OTHER	Flickering light stimuli	The intervention will be exposed to flickering lights (≤200 lux). More specifically, the participants will be asked to be exposed to a specified flickering light (1Hz, 30 seconds On, and 30 seconds OFF) for 2 hours starting at their habitual bedtime (HBT).
OTHER	Constant light stimuli	The intervention will be exposed to constant background lights (≤200 lux). The participants will be asked to be exposed to a specified constant light for 2 hours starting at their habitual bedtime (HBT).
OTHER	Dim light	This light condition is the baseline (≤10 lux).

Timeline

• Start date: 2022-06-20
• Primary completion: 2023-03-15
• Completion: 2023-09-15
• First posted: 2022-06-21
• Last updated: 2022-06-21

Locations

1 site across 1 country: Switzerland