Season mood changes are a phenomenon recognised by almost everyone. Who did never experience a little energy decrease or light depressive feelings with the beginning of Autumn or Winter? And the season recurrence of some Psychiatric Disorders, like MDD and BD are sufficiently acknowledged by patients and specialists. There is even a nosologic entity called Seasonal Affective Disorder, which shows more prevalence among Nordic places (where winter days are shorter) and in which light therapy seems a good therapeutic option. Not only in Psychiatry the properties of light therapy were recognised, NR Finsen won the Nobel Prize in 1903 for his work with Heliotherapy (found benefits with sun exposure in some skin diseases). There are various theories that try to explain those assumptions, like summer-winter difference in duration of nightly melatonin release, inability to synchronize circadian rhythms with sleep/wake rhythms and even Vitamin D production.

The aim of this work consists on a scientific revision of the origins and the influence extension of seasonality in Psychiatric Disorders (PD) and in therapeutic implications, particularly with some new anti-depressants.

We make a bibliographic investigation about more recent findings in origins and influence extension of seasonality in PD and the role of new psychopharmacologic approaches in these cases.

There are some scientific papers in which those maters are analysed.

There are some scientific theories about the mechanisms and degree of influence of seasonality in some PD, but the whole process have not been explained nor have been tested.