Major depressive disorder with seasonal pattern

Major depressive disorder with seasonal pattern (MDDSP)... 

Major depressive disorder with seasonal pattern (MDDSP) is characterized, clinically, by a depressed mood that occurs at the same time each year, virtually every year since the disorder was first experienced. These depressive states (usually modest) are often termed winter depression since they worsen as the duration of light hours is reduced during the year. The prevalence of MDDSP is estimated to be around 5% in the USA and women are affected five times more than men. As the population is located further from the equator, more people are affected. 

Some depressed patients, especially if younger, lethargic and/or bipolar, complain of hypersomnia rather than of insomnia [16], Recurrent winter oversleeping is even considered as a key symptom to diagnose seasonal affective disorder (SAD). Several sleep EEG studies were performed in patients with SAD and none could evidence the typical sleep pattern of major depression (see [10]). Polysomnographic studies... 

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