Ah .... now I know why I've been so gloomy and lethargic today

Sun flares are to blame.  No, seriously ... it's true !    Earthquakes and sun flares are mainly to be blamed for our mood swings.

From SpaceWeather:
Humongous eruption:  A truly gigantic explosion happened on the sun yesterday. On Nov. 16th, magnetic fields snaking halfway across the sun's southern hemisphere erupted in tandem, producing a prominence so big, it doesn't fit inside this image from NASA's Solar Dynamics Observatory (SDO):


The two articles below are from several months ago.

David Shiga writing at TheNewScientist
The sun is gearing up    for a peak in activity at a time when technology makes our planet more vulnerable to solar outbursts than ever before. Monitoring has improved since the last solar maximum, so what are the big risks this time around?
About once every 11 years, the sun goes ballistic, throwing out more bursts of magnetic activity than normal. As a large but harmless solar flare signalled last week, the next solar maximum is due in 2013.......

Catherine Brabic writing at TheNewScientist
....Many animals can sense  the Earth's magnetic field, so why not people, asks Oleg Shumilov of the Institute of North Industrial Ecology Problems in Russia.
Shumilov looked at activity in the Earth's geomagnetic field from 1948 to 1997 and found that it grouped into three seasonal peaks every year: one from March to May, another in July and the last in October.
Surprisingly, he also found that the geomagnetism peaks matched up with peaks in the number of suicides in the northern Russian city of Kirovsk over the same period.
Shumilov acknowledges that a correlation like this does not necessarily mean there is a causal link, but he points out that there have been several other studies suggesting a link between human health and geomagnetism.
For example, a 2006 review of research on cardiovascular health and disturbances in the geomagnetic field in the journal Surveys in Geophysics (DOI: 10.1007/s10712-006-9010-7) concluded that a link was possible and that the effects seemed to be more pronounced at high latitudes.....