Seasonal affective disorder (SAD) - Symptoms and causes - Mayo Clinic
Firstly, get your Vit D levels sufficient, get a test but you can be almost sure of the deficiency when no SUN. And if you are not supplementing. I know Vit D and deficiency has been discussed here plenty of times, but a reminder as I run into so many irritated, angry, depressed people and go right to the SUNSHINE happy support.
Sun has been absent a lot so far this winter even here in So Cal.