Impaired sleep quality and dyssomnia disorders in particular have repeatedly been linked to affective symptoms. However reports about systematic assessments in larger study samples are generally lacking. Furthermore the associative relationships of fatigue and sleepiness complaints to sleep quality and affective symptoms are poorly described.

During a one-year period we recruited 570 patients (mean age 28(0.26), 287 males) attending the sleep laboratory of a general University Hospital. Psychometrics were performed using the Pittsburgh Sleep Quality Index (PSQI), the Hospital Anxiety and Depression Scale (HAD), the Fatigue Severity Scale (FSS) and the Epworth Sleepiness Scale (ESS). All patients underwent two consecutive nights of full polysomnographic recording (PSG).

Both fatigue (FSS) and sleepiness (ESS) were related to affective symptoms (HAD, p< 0.001 and p=0.012 respectively). Fatigue and affective symptom intensity but not sleepiness, were correlated to sleep quality (p< 0.001). The HAD was related to REM-Sleep Latency (HAD, p=0.017). Slow Wave Sleep duration of the second night was negatively correlated to affective symptoms (p=0.21). Body mass index (BMI) was correlated to fatigue (p< 0.001), sleepiness (p=0.18) and to sleep quality (p=0.006) but not to affective symptoms.

These results confirm the tight relations between sleep quality, daytime fatigue or sleepiness and affective symptoms. Residual fatigue is a common and invalidating complaint in mental disorders as major depression. Achievement of clinical remission can be compromised because of residual treatment resistant symptoms. PSG might be useful in certain conditions to rule out co-morbid sleep disorders and to orientate treatment attitudes.