The reliability and validity of the Seasonal Pattern Assessment Questionnaire: a comparison between patient groups.

Background: The Seasonal Pattern Assessment Questionnaire (SPAQ) is a frequently used screening instrument in the research on Seasonal Affective Disorder (SAD). Nevertheless, studies on its reliability and validity are relatively scarce. In the present study the reliability and the contrast validity of the SPAQ are investigated.

Mood regulation in seasonal affective disorder patients and healthy controls studied in forced desynchrony.

In healthy subjects, both the duration of wakefulness and the circadian pacemaker have been demonstrated to be involved in the regulation of mood. Some features of affective disorders suggest that these two factors also play a role in the dysregulation of mood. In particular, disturbances of the circadian pacemaker have been proposed to be a pathogenetic factor in Seasonal Affective Disorder, winter type (SAD).

Sleep in seasonal affective disorder patients in forced desynchrony: an explorative study.

The majority of winter-type seasonal affective disorder (SAD) patients complain of hypersomnia and daytime drowsiness. As human sleep is regulated by the interaction of circadian, ultradian and homeostatic processes, sleep disturbances may be caused by either one of these factors. The present study focuses on homeostatic and ultradian aspects of sleep regulation in SAD.

A forced desynchrony study of circadian pacemaker characteristics in seasonal affective disorder.

The circadian pacemaker is an endogenous clock that regulates oscillations in most physiological and psychological processes with a near 24-h period. In many species, this pacemaker triggers seasonal changes in behavior. The seasonality of symptoms and the efficacy of light therapy suggest involvement of the circadian pacemaker in seasonal affective disorder (SAD), winter type.