Reduced sunlight and the change in season can cause a drop in serotonin levels — which affect mood — and impact melatonin levels, important for sleep patterns, in the body.
Rodgers, the Sacramento area clinical psychologist, said the fall and winter months can also evoke grief for some because of the holidays.
"Sometimes people's grief is more activated around this time, simply, because you know, they'll have to go through this holiday without that loved one," she said.
Rodgers said that some people may also have difficulty with this time of year because of complications with family relationships.
Risk factors of S.A.D.
Kimberly Miller, a practicing neuropsychologist and owner of Health Mind Sacramento Psychological Services, said that people who have prior depression or tendencies to have depression symptoms are likely to experience S.A.D.
"They might find themselves dealing with listless or low energy or just wanting to sleep more," Miller said, adding that these are symptoms of depression.
According to the Mayo Clinic, S.A.D. is also common among individuals who live further north or south of the equator due to less sunlight exposure in these areas in the winter and longer days in the summer.
Miller said that sunlight is directly tied to seasonal affective symptoms.
People get vitamin D from sunlight, she explained, which affects the chemicals in the brain that are related to mood.