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

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: 1. psychiatric diseases according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria;15 2. cognitive or neurological disorders; 3. alcohol or substance abuse; 4. unstable or serious medical illness; 5. current use of psychoactive mediations including antidepressants, anxiolytics, neuroleptics, anticonvulsants, hypnotics, or stimulant medications; 6. primary sleep disorder; 7. habitual sleep onset earlier than 21:00 or later than 24:00; 8. shift worker; 9. travel across more than two time zones within 90 days of the study; and 10. ophthalmologic disease during the study period.