A Study on the Changes of the Biological Rhythm by Display Image Modulation

Study Overview
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Brief Summary
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Effects of Smartphone Use at Night with Light Emitting Diode Display With and Without Blue Light in Healthy Adults: A Randomized, Double-blind, Cross-over, Placebo-controlled Comparison

Conditions
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Circadian Rhythm Phase Shift

Intervention / Treatment
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* Device: smartphone display


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: (1) Healthy males 20-40 years of age who understood the study procedure and agreed to participate after being fully informed about the study were included. Exclusion Criteria: psychiatric diseases according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria;15 cognitive or neurological disorders; alcohol or substance abuse; unstable or serious medical illness; current use of psychoactive mediations including antidepressants, anxiolytics, neuroleptics, anticonvulsants, hypnotics, or stimulant medications; primary sleep disorder; habitual sleep onset earlier than 21:00 or later than 24:00; shift worker; travel across more than two time zones within 90 days of the study; and ophthalmologic disease during the study period.

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Screening
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: LED with bluelight<br>Two types of smartphone were used. One type had a conventional LED display with the full range of blue light. The LED in the other type newly developed by Samsung Display was suppressed for the blue light portion of the spectrum (wavelength 450   470 nm). The smartphones were indistinguishable from each other with the naked eye, because other wavelengths mimicked blue light in the suppressed LED. | Device: smartphone display<br> <br> |
| Experimental: LED without bluelight<br>Two types of smartphone were used. One type had a conventional LED display with the full range of blue light. The LED in the other type newly developed by Samsung Display was suppressed for the blue light portion of the spectrum (wavelength 450   470 nm). The smartphones were indistinguishable from each other with the naked eye, because other wavelengths mimicked blue light in the suppressed LED. | Device: smartphone display<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes of serum melatonin |  | serum melatonin levels were measured every 60 min from 7:00 PM on day 1 to 8:00 AM on day 2, from 7:00 PM on day 2 to 8:00 AM on day 3, and from 7:00 PM to 11:00 PM on day 3 for 3 days. | 
| Changes of serum cortisol |  | cortisol levels were measured every 120 min from 7:00 PM on day 1 to 8:00 AM on day 2, from 7:00 PM on day 2 to 8:00 AM on day 3, and from 7:00 PM to 11:00 PM on day 3 for 3 days. | 
| Changes of body temperature |  | body temperature was measured every 120 min from 7:00 PM on day 1 to 8:00 AM on day 2, from 7:00 PM on day 2 to 8:00 AM on day 3, and from 7:00 PM to 11:00 PM on day 3 for 3days. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| profile of mood states(POMS) | Mood was measured using the POMS,17 a well-validated self-report measure of mood states. | day 1,3 | 
| Epworth Sleepiness Scale(ESS) | ESS18 is comprised of eight questions that query the subject's likelihood of dozing off or falling asleep in a particular situation that is commonly met in daily life. | day 1,3 | 
| Fatigue severity scale(FSS) | The FSS20 is composed of 9 statements (items) that describe fatigue symptoms. Respondents select the most relevant level of agreement over the last week on a 7-point scale (1 strongly disagree; 7 strongly agree). | day 1,3 | 
| continuous performance test(CPT) | Integrated visual-auditory CPTs were performed at days 1 and 3 by a psychologist who was an expert on cognitive tests | day1,3 |