Oh yes, lack of sunshine really does make you tired and depressed. Like one of the PP's said, it's called Seasonal Affective Disorder (SAD - an appropriate acronymn!). I have SAD - I grew up in MN, then moved to WI for college, grad school, job, etc. for 10 years, and I would always start to droop in mid October, wilt when DST ended, hibernate through February, and suddenly start to come back to life in March. My roommate used to tell me that she always felt like she lost me for 6 months of the year! I finally started getting treatment for SAD in grad school, and it totally made a difference! I needed mild anti-depressants (with an increased dose from Oct-Feb) and I used a light box every morning in the winter.
My doctor kept advising me to move somewhere that got more sunshine, but I resisted. Then I met DH, got married, and moved out to CA (where DH has lived since he was 3). Now I live in a city that averages 300 days of sunshine a year! Hooray! I still get droopy when it's the rainy season (i.e. winter), but it isn't anywhere near as bad as it was when I lived in the Midwest.