A Circadian Vulnerability for Depression: Eveningness and Sleep Variability

• Other Authors: Bernert, Rebecca A. (authoraut)
• Format: Others
• Language: English; English
• Published: Florida State University
• Subjects: Psychology
• Online Access: http://purl.flvc.org/fsu/fd/FSU_migr_etd-1370

Circadian rhythms describe behavioral and biological variables that demonstrate a periodicity of approximately 24 hours. Although such rhythms show consistent 24-hour patterns, differences exist in the timing of circadian phase position. Extreme diurnal preferences are referred to as eveningness and morningness. Despite a growing interest in the study of circadian rhythm abnormalities and psychopathology, diurnal preferences have been relatively understudied in depression. The present study examined these preferences in a sample of 82 college undergraduates. Due to a presumed desynchrony between sleep and circadian preference, evening types were hypothesized to show increased sleep variability and the highest levels of depressive symptoms. Sleep variability was expected to mediate the link between eveningness and depressive symptoms. Results first revealed that diurnal preferences did not significantly predict depressive symptoms, although this association emerged as a nonsignificant trend (p = .08). Next, diurnal preferences significantly predicted sleep variability (p = .03). Sleep variability did not uniquely predict depressive symptoms, although this link also emerged as a non significant trend (p = .05). Finally, a mediation model was not supported at the p < .05 level (p = .15). === A Thesis Submitted to the Department of Psychology in Partial Fulfillment of the Requirements for the Degree of Master of Science. === Fall Semester, 2005. === July 20, 2005. === Diurnal Preferences, Mood Disturbances, Sleep Rhythms === Includes bibliographical references. === Thomas Joiner, Professor Directing Thesis; Janet Kistner, Committee Member; Frank Johnson, Committee Member.