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

NCT ID: NCT05423002

Last Updated: 2022-06-21

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

UNKNOWN

Clinical Phase

NA

Total Enrollment

68 participants

Study Classification

INTERVENTIONAL

Study Start Date

2022-06-20

Study Completion Date

2023-09-15

Brief Summary

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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

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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

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Light Flashing

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

CROSSOVER

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

SINGLE

Outcome Assessors

Study Groups

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Control

Dim light condition as a baseline

Group Type PLACEBO_COMPARATOR

Dim light

Intervention Type OTHER

This light condition is the baseline (≤10 lux).

Modulation

Flickering light will be added sinusoidally onto the background light.

Group Type ACTIVE_COMPARATOR

Flickering light stimuli

Intervention Type OTHER

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).

Background

Constant light with maximum half irradiance (50%) of all primaries.

Group Type SHAM_COMPARATOR

Constant light stimuli

Intervention Type OTHER

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).

Interventions

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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).

Intervention Type 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).

Intervention Type OTHER

Dim light

This light condition is the baseline (≤10 lux).

Intervention Type OTHER

Eligibility Criteria

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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


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

18 Years

Maximum Eligible Age

35 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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Horizon 2020 - European Commission

OTHER

Sponsor Role collaborator

University of Basel

OTHER

Sponsor Role lead

Responsible Party

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Fatemeh Fazlali

Investigator

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Christian Cajochen, Prof

Role: PRINCIPAL_INVESTIGATOR

Centre for Chronobiology, UPK, University of Basel

Locations

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Centre for Chronobiology

Basel, , Switzerland

Site Status

Countries

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Switzerland

Central Contacts

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Fatemeh Fazlali, MSc

Role: CONTACT

+41(0) 61 325 5478

Christian Cajochen, Prof

Role: CONTACT

+41(0) 61 325 5318

Facility Contacts

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Christian Cajochen, Prof

Role: primary

+41(0) 61 325 5318

Other Identifiers

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ID 2022-00401

Identifier Type: -

Identifier Source: org_study_id

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