I’ve read a lot over the years about S.A.D. Seasonal Affective Disorder is described as a depression that occurs at the same time every year . Commonly, when seasons change towards the end of the year. Fall to winter. Darker days.
SAD is a real condition . I know people who struggle during these times . There are special lights and lamps that are helpful . People try to stay outdoors as long as possible to ease the symptoms . It’s a difficult time.
“Light therapy boxes can offer an effective treatment for seasonal affective disorder. Features such as light intensity, safety, cost and style are important considerations. Seasonal affective disorder (SAD) is a type of depression that typically occurs each year during fall and winter.”- Mayo Clinic

I don’t knock people that struggle during these times. Depression is depression as far as I’m concerned .
Please speak to your doctor if your “sadness” becomes unbearable . Therapists and psychiatrists will be able to help you get through the darker days .

https://www.amazon.com/NatureBright-SunTouch-Light-Therapy-package/dp/B000W8Y7FY