I have decided (as I said in a comment over at MauiGirl´s place) that I am suffering from reverse-SAD. Instead of being berflibbeted by a lack of sunlight, I am off my game because of too much.
Here in the Tropics (a mere 10º North of the Equator) "day" varies by only about ... well, I can´t find the info right now, but it ain´t much. Sunrise around 5AM (yes) and sunset around 6PM all year long.
So I´m not getting that welcome break (for me, freak that I am) from daylight that winter normally brings. And the sun is also, as one of my students said yesterday, "heavy" -- that´s apparently how Costa Ricans describe the intensity of the Tropical sun. Even when it´s cool, it´s hot.
Anyway, I´ll get used to it as time goes by... and I get to wear shorts all the time!