[Onscreen text:
The Ohio State University
Wexner Medical Center
What is SAD, and why does it happen?]

D. Gage Jordan, PhD:
Seasonal affective disorder is a subtype of clinical depression, and it's a really important subtype or specifier for depression because it tells us that depression is a little bit more full-blown, a little bit more prevalent within certain seasons of the year. 

[Onscreen text:
D. Gage Jordan, PhD
Psychologist
Ohio State Wexner Medical Center]

Dr. Jordan:
Seasonal affective disorder, at least within our country and the northern hemisphere and North America is a little bit more prevalent within the later fall months and throughout the winter months. There are a couple reasons why seasonal affective disorder tends to pop up around late fall and throughout the winter months. Oftentimes we think about biological causes for seasonal affective disorder. Some of the things that the scientific literature points to would be aspects of neurotransmitter functioning. Things like serotonin, which is an important neurotransmitter for mood regulation, is a little less active throughout the winter months. That can be the basis for certain treatments like antidepressants, things like Prozac or Wellbutrin, for example, tend to regulate or modulate levels of serotonin within the brain.
Winter months, since it's a little bit darker earlier within the day, scientific literature also suggests that melatonin, which is a hormone that promotes sleepiness, is a little bit more active within the winter months as well. And that can lead to certain symptoms of seasonal affective disorder such as low energy and low mood as well. We often see that vitamin D can be deficient in people struggling with seasonal affective disorder. Research literature is a little bit mixed on that as a singular cause for seasonal affective disorder, but sometimes vitamin D supplement can help, but I would encourage people to consult with their primary care physician if they think that's the case as well. We often think about depression from what we call a biopsychosocial model. So basically three domains or three categories of things that we believe contribute to depression. So at a biological level, especially for seasonal affective disorder, we can think about things like serotonin, melatonin and vitamin D deficiencies.
When we think about a psychological perspective, we think about how the person's behavior might contribute to their feelings of depression. How they regulate their emotions and what their thinking patterns might be. When we think about a social perspective, we think about the things that are happening in society that might impact depression or seasonal affective disorder. When we think about these psychological factors, we often want to make sure that our behavior is stabilized. We're continuing to engage in activities that promote a sense of wellbeing, that are values-based, that provide a sense of meaning as well, especially throughout the winter months. Some of those activities may be a little less available, especially in comparison to the summer months. When we think about some of the social factors, oftentimes winter can be a really stressful environment for a lot of different types of people. We think about the holidays and the new year, for example.
Thanksgiving, Christmas, New Year travels, things like that can be something that's difficult for people. We might not be able to control those types of things, but we also want to think about how we might be able to prevent them or maybe cope ahead as well.

[Onscreen text:
The Ohio State University
Wexner Medical Center
For more information, visit:
health.osu.edu]