Excessive daytime sleepiness and fatigue in depressed patients and therapeutic response of a sedating antidepressant

BACKGROUND: Although sleepiness and fatigue are common symptoms in depressed patients, the relationships among sleepiness, fatigue and treatment of depression have not been fully elucidated. The main objective of this study was to investigate the therapeutic effects of a sedating antidepressant on sleepiness and fatigue in patients with depression. METHODS: Forty-two depressed patients, who met DSM-IV diagnostic criteria, and 32 matched healthy controls participated in the baseline measurements. Sixteen of the depressed patients were treated with mirtazapine. At baseline, daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS) and Stanford Sleepiness Scale (SSS), and fatigue was assessed using the Fatigue Severity Scale (FSS) and Fatigue Impact Scale (FIS). During treatment, Multiple Sleep Latency Test (MSLT), ESS and SSS were used to measure daytime sleepiness, and the FIS, FACES Checklist-Fatigue subscale (FAF) and Fatigue Assessment Instrument (FAI) were used to measure fatigue. RESULTS: At baseline, there were significant group differences between the depressed and healthy controls on the ESS (P = 0.001), SSS (P<0.001), FSS (P < 0.001) and FIS (P < 0.001). Significant improvement of sleepiness and fatigue measures was seen after treatment with mirtazapine on the MSLT (P = 0.011), ESS (P = 0.021), SSS (P = 0.001), FIS (P = 0.002) and FAF (P = 0.004). LIMITATIONS: Open-label treatment and relatively small sample size. CONCLUSION: Daytime sleepiness and fatigue are significant symptoms in depressed patients. Slightly paradoxically, a sedating antidepressant may alleviate these symptoms.