In just a couple weeks, (November 2nd), we will turn our clocks back an hour. And, the days do seem shorter--it's dark when I wake up and it's dark long before I go to bed.
Many of us struggle to adjust to the change for a few weeks, but weather it. For others, seasonally worsening mood is an aspect of dealing with a major mood disorder. People often complain of sleeping too much, gaining weight, and feeling perpetually fatigued, along with feeling more depressed.
Seasonal affective disorder isn't it's own diagnosis, per se, but a way of describing the changes in a person's mood as it is impacted by the seasons.
Things that seem to help manage a worsening mood associated with the shorter days include getting exercise, getting outside, even a little bit each day to get some sunlight, and adding an antidepressant (for those solely on mood stabilizers) or an increase in antidepressant during the dark months.
If you look back on prior periods of worsening depression, and recognize that they tend to happen during the winter months, now is the time to make a strategic coping plan. Talk to your provider about a med adjustment, and talk to your therapist about behavior changes to help you get outside each day, get more exercise, make sure the blinds and curtains are open in your home and office, etc.