SAD

Feeling blue, fatigued, and withdrawn when the days are shorter are signs of a type of depression called seasonal affective disorder (SAD). Researchers are still determining what causes SAD. Most research to date has investigated potential causes of winter-pattern SAD because it is more common and easier to study. As a result, less is known about summer-pattern SAD, and more research is needed.

Studies indicate that people with SAD, especially winter-pattern SAD, have reduced levels of the brain chemical serotonin, which helps regulate mood. Research also suggests that sunlight affects levels of molecules that help maintain normal serotonin levels. Shorter daylight hours may prevent these molecules from functioning properly, contributing to decreased serotonin levels in the winter. Michigan winters often do not provide much sun, so Michiganders are more prone to SAD that sunnier states, like Florida.

Vitamin D deficiency may exacerbate these problems in people with winter-pattern SAD because vitamin D is believed to promote serotonin activity. In addition to vitamin D consumed in food, the body produces vitamin D when exposed to sunlight on the skin. With less daylight in the winter, people with SAD may have lower vitamin D levels, further reducing serotonin activity.

Other studies suggest that both forms of SAD relate to altered levels of melatonin—a hormone important for maintaining the normal sleep−wake cycle. People with winter-pattern SAD produce too much melatonin, which can increase sleepiness and lead to oversleeping.

In contrast, people with summer-pattern SAD may have reduced melatonin levels, consistent with long, hot days worsening sleep quality and leading to depression symptoms. Longer daylight hours, shorter nights, and high temperatures can also cause sleep disruptions. However, these theories have not been systematically tested.

Both serotonin and melatonin help maintain the body’s daily rhythm tied to the seasonal night−day cycle. In people with SAD, changes in serotonin and melatonin disrupt normal daily rhythms. As a result, they can no longer adjust to seasonal changes in day length, leading to sleep, mood, and behavior changes.

Negative thoughts and feelings about the winter or summer and its associated limitations and stresses are also common among people with SAD (as well as others). It is unclear, however, whether these thoughts are causes or effects of the mood disorder, but they can be a useful focus of treatment.

If you struggle with seasonal affective disorder symptoms, or wonder if you have it, Andrea can provide the answers and support you need. She understands how SAD can take over your life and provides the support and tools you need to regain control. She can order a Vitamin D level and see if you need additional supplementation.

Call Total Clarity Psychiatry today or schedule an appointment with Andrea online to get treated. Click on the “BOOK NOW” link to see her availability.

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