Thank you for your question!
First of all, you need a consultation with a specialist, and diagnosis, if you have Seasonal Affective Disorder (SAD). This is a very common thing that occurs in people with a lack of sunlight - then more than needed the hormone melatonin, which is normally responsible for healthy sleep, begins to be released, and your rhythms go to hell. In particular, insomnia can be added to sleepiness and apathy - then the light will not be nice at all. Read more in Wikipedia.
In order to overcome drowsiness and apathy in the fall, it is recommended to take vitamins, especially of group B, load yourself physically, monitor the rhythms of sleep and wakefulness, and also monitor nutrition; even invented special lamps that simulate daylight, they are still expensive in our country, and there are few research materials - but in general they are used in some places and you can read about this too.
All this has contraindications and is necessary consult a doctor. Success in the fight!
Take a vacation or leave work, if you suddenly have savings, and do what you really want for a long time. Go to the skating rink, go skiing, visit, invite, come up with gifts for friends. This is how you start doing it - no apathy, no drowsiness. Because apathy comes when you're doing something boring or just boring. And if she came, then you are tired of work. At least that's how it happens with me. You need to reboot and look around.