UVM Theses and Dissertations
Camuso, Julia Anne
Winter seasonal affective disorder (SAD) is a recurrent subtype of major depressive disorder that onsets in the fall and winter and remits in the spring and summer. Hypersomnia is the most common sleep problem in SAD based on self-report measures, but studies using behavioral measures of sleep patterns in SAD are needed to corroborate this. The present study assessed behavioral (via actigraphy) and self-reported (via daily sleep diaries) sleep patterns, fatigue catastrophizing (FC; i.e., excessively negative expectations about fatigue), and depression severity in 91 currently depressed SAD patients. Participants were grouped according to sleep problems endorsed during clinical interview covering the past week: 49(53.8 %) endorsed insomnia only, 28 (30.8%) reported no sleep disturbance, 7 (7.6%) endorsed hypersomnia only, and 7 (7.6%) endorsed both hypersomnia and insomnia. Analyses of variance (ANOVA) indicated no significant differences between sleep diary and actigraphy assessed sleep behaviors. Bland-Altman analyses indicated agreement between actigraphic and self-reported total sleep time (TST) and time in bed (TIB), but poor agreement between methods for wake after sleep onset (WASO). Hypersomnia only participants endorsed significantly less severe FC compared to participants with no sleep disturbance. Regression analyses indicated that (a) the interaction between fatigue severity and FC significantly predicted self-reported WASO, (b) FC predicted actigraphic TST and TIB, and (c) FC and fatigue severity significantly predicted depression severity. Self-reported and actigraphic sleep variables did not predict depression severity. Over half of this sample endorsed insomnia without hypersomnia and only about 15% endorsed hypersomnia with or without accompanying insomnia on clinical interview, indicating that hypersomnia may be less common among SAD patients than previously believed. Relative to behavioral sleep measures, these SAD patients had relatively accurate perceptions of their total times asleep and in bed, but inaccurate perceptions of their nocturnal wake time. The latter may be a cognitively driven phenomenon, whereby catastrophic thoughts about fatigue interact with state fatigue to influence self-reports of awakenings after sleep onset.
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