Light FlashingCONENCT05423002
Effect of Different Color Lights on the Internal Clock and Alertness in Humans
A study testing Flickering light stimuli, Constant light stimuli and Dim light in people with Light Flashing, run by University of Basel at 1 site in Switzerland.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 35 yearsHealthy volunteers can take part
- Conditions the study is for
- Light Flashing
- What is being tested?
- Flickering light stimuli, Constant light stimuli and Dim light
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 68 participants
- Where
- 1 siteSwitzerland
- Study dates
- 20 Jun 2022to 15 Sep 2023
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 35 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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)
Who cannot join
- 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
Show all 14Show fewer
- 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
Trial locations and contacts
1 site in 1 country.
Switzerland1 site
Centre for Chronobiology
Basel, 4002
Christian Cajochen, Prof, +41(0) 61 325 5318, Christian.Cajochen@upk.ch
About this study
Official title: Mechanisms of Cone Photoreceptors Contribution on Human Neuroendocrine Physiology and Pupillary Light Responses
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.
Read the 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
- Being tested
- Flickering light stimuli, Constant light stimuli, Dim light
- Keywords
- Flickering light, Photoreceptors, Cones
- Medical subject headings
- photopsia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Flickering light stimuliOther
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).
Constant light stimuliOther
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).
Dim lightOther
This light condition is the baseline (≤10 lux).
| Study group | Role | What they receive |
|---|---|---|
| Control | Placebo comparator | Dim light condition as a baseline Receives: Other: Dim light |
| Modulation | Active comparator | Flickering light will be added sinusoidally onto the background light. Receives: Other: Flickering light stimuli |
| Background | Sham comparator | Constant light with maximum half irradiance (50%) of all primaries. Receives: Other: Constant light stimuli |
What is being measured
The primary outcome is the main question the study is designed to answer.
Melatonin concentration
The saliva samples will be collected from participants every 30 min. The investigators hypothesize that the cone flickering light stimuli will have a different melatonin-attenuating effect than the constant background stimuli and that both will have a different effect than baseline.
Measured: 1 year
Secondary outcomes (5)
Vigilance performance
Sustained attention performance will be assessed throughout the study, using an auditory psychomotor vigilance test (PVT) approach. The investigators hypothesize that the flickering light stimuli will produce different reaction times as measured with the PVT than constant light and baseline. Besides, the baseline will not yield the same reaction times as constant background light.
Measured: 1 year
Subjective sleepiness
The investigators will collect subjective sleepiness ratings using the one-question 9-point Karolinska Sleepiness Scale. The investigators hypothesize that sleepiness (ratings) will be different in the flickering light stimuli than in the constant background light and both will be different than baseline.
Measured: 1 year
Visual comfort
To assess each participant's subjective perception of visual comfort, The investigators will use a custom 7-point rating scale that probes brightness, light color, and glare perception based on a selection of questions. The investigators hypothesize that visual discomfort ratings will change in the flickering light stimuli in comparison to the constant background stimuli and baseline.
Measured: 1 year
Skin temperature
The investigators will monitor skin temperatures using six surface temperature thermocouples (BS 1922L Thermochron iButton®, Maxim, US) placed on proximal and distal regions of the body surface. The investigators hypothesize that the temperature of the body skin will be different in the flickering light stimuli than in the constant stimuli and both will have a different effect in comparison to the baseline.
Measured: 1 year
Pupil response
The investigators will measure changes in the pupil area using a silent substitution Pupillograph. The investigators hypothesize that the pupil constriction will be different after exposure to the light conditions as cones and post-receptoral channels adapt to the light stimuli. Besides, the pupil constriction will change differently under the cone-modulated light when the direction of stimuli is identical to the direction of flickering light condition.
Measured: 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Jun 2022
- Study start20 Jun 2022 (estimated)
- Primary completion15 Mar 2023 (estimated)
- Study completion15 Sep 2023 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Light FlashingStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 68 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Basel
- Sponsor type
- University, hospital or other
- Collaborators
- Horizon 2020 - European Commission
- Responsible party
- Principal investigator, Fatemeh Fazlali, University of Basel
- Investigators
- Christian Cajochen, Prof, Principal investigator, Centre for Chronobiology, UPK, University of Basel
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05423002
- Sponsor's protocol ID
- ID 2022-00401
- Acronym
- CONE
- Status last verified
- Jun 2022
- First submitted
- 7 Jun 2022
- Last updated
- 21 Jun 2022
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: As the investigators have a plan to submit the study to a registered report journal. The investigators would prefer to share the data after submission.
Study at a glance
From the registry record, last updated by the sponsor on 21 Jun 2022. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Mechanisms of Cone Photoreceptors Contribution on Human Neuroendocrine Physiology and Pupillary Light Responses
- ClinicalTrials.gov ID
- NCT05423002
- Acronym / sponsor ID
- CONE / ID 2022-00401
- Conditions
- Light Flashing
- Keywords
- Flickering light, Photoreceptors, Cones
- Study type
- Interventional
- Recruitment status
- Unknown status
- Enrolment
- 68 participants (estimated)
- Lead sponsor
- University of BaselUniversity, hospital or other
- Collaborators
- Horizon 2020 - European Commission
- Study start
- 20 Jun 2022 (estimated)
- Primary completion
- 15 Mar 2023 (estimated)
- Study completion
- 15 Sep 2023 (estimated)
- First posted
- 21 Jun 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Control | Placebo comparator | Other: Dim lightDim light condition as a baseline |
| Modulation | Active comparator | Other: Flickering light stimuliFlickering light will be added sinusoidally onto the background light. |
| Background | Sham comparator | Other: Constant light stimuliConstant light with maximum half irradiance (50%) of all primaries. |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- 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)
Key exclusion criteria (14 listed)
- 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)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Flickering light stimuliThe 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 | Modulation |
| Constant light stimuliThe 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 | Background |
| Dim lightThis light condition is the baseline (≤10 lux). | Other | Control |
Primary outcome
Melatonin concentration
Time frame: 1 year
The saliva samples will be collected from participants every 30 min. The investigators hypothesize that the cone flickering light stimuli will have a different melatonin-attenuating effect than the constant background stimuli and that both will have a different effect than baseline.
5 secondary outcomes
Vigilance performance
Time frame: 1 year
Subjective sleepiness
Time frame: 1 year
Visual comfort
Time frame: 1 year
Skin temperature
Time frame: 1 year
Pupil response
Time frame: 1 year
Results and safety
Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 21 Jun 2022.
- Individual participant dataSharing planned: No. As the investigators have a plan to submit the study to a registered report journal. The investigators would prefer to share the data after submission.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Christian Cajochen, Prof principal investigator
Centre for Chronobiology, UPK, University of Basel
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Flickering light stimuli, Constant light stimuli and Dim light in people with Light Flashing, run by University of Basel at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 14 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: status not confirmed, as of the sponsor's last update on 21 Jun 2022. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
Contact Fatemeh Fazlali, MSc (+41(0) 61 325 5478, fatemeh.fazlali@unibas.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Melatonin concentration (time frame: 1 year). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 Jun 2022.