Clinical trial NCT05423002: Effect of Different Color Lights on the Internal Clock and Alertness in Humans
Official title: Mechanisms of Cone Photoreceptors Contribution on Human Neuroendocrine Physiology and Pupillary Light Responses
Study type: INTERVENTIONAL
Overall status: UNKNOWN
Phase: NA
Conditions: Light Flashing
Keywords: Flickering light
Photoreceptors
Cones
Lead sponsor: University of Basel
Sponsor class: OTHER
Collaborators: name: Horizon 2020 - European Commission
First posted: 2022-06-21
Enrollment: 68
Sex: ALL
Minimum age (years): 18
Maximum age (years): 35
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: BASIC_SCIENCE

Brief 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.

Eligibility criteria: Inclusion Criteria:

* Age: 18 - 35 years
* Sex: male or female normal color vision, male dichromat (i.e. tested by CCT, HRR, Farnsworth Munsell 100 Hue Test)
* BMI: 18.5 - 29.9 self-reported weight and height (i.e. normal and overweight according to WHO)
* Signed consent form of participants
* Chronotype: Morningness-Eveningness Questionnaire (31 - 69)
* Sleep Quality: Pittsburgh Sleep Quality Index, PSQI (≤5)

Exclusion Criteria:

* High myopia (\> -6 diopters)
* High hyperopia (\< +6 diopters)
* 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
* Ophthalmological or optometric conditions (cataract, glaucoma, retinal detachment, macular conditions, chronic inflammations, eye injuries, or operations)
* General health concerns or disorders, including heart and cardiovascular, neurological, nephrological, endocrinological, and psychiatric conditions
* Medication impacting on visual, neuroendocrine, sleep, and circadian physiology
* For females only: pregnancy, use of hormonal contraceptives, lactation or breastfeeding
* Drug (urinary drug screening) and alcohol use
* Non-compliance with sleep-wake times: \>1 deviation from ±30 minute window sleep and wake-up time
* Extreme chronotype (Munich Chronotype Questionnaire \<2 or \>7)
* Current participation in other clinical trials

Exclusion criteria due to study requirements:

* Inability to understand and/or follow study materials or procedures
* Insufficient knowledge of project language

Primary outcomes:
measure: Melatonin concentration
timeFrame: 1 year
Secondary outcomes:
measure: Vigilance performance
timeFrame: 1 year
measure: Subjective sleepiness
timeFrame: 1 year
measure: Visual comfort
timeFrame: 1 year
measure: Skin temperature
timeFrame: 1 year
measure: Pupil response
timeFrame: 1 year
Other outcomes:
Locations:
city: Basel
country: Switzerland
facility: Centre for Chronobiology
Study officials:
affiliation: Centre for Chronobiology, UPK, University of Basel
name: Christian Cajochen, Prof
role: PRINCIPAL_INVESTIGATOR
References: