Final answer:
Brenda likely has Seasonal Affective Disorder (SAD), a mood disorder with increased depressive symptoms during winter. Melatonin plays a role in SAD due to changes in light exposure.
Step-by-step explanation:
Brenda experiences depression each winter, which has occurred consistently for the past three years. This pattern suggests that she might be suffering from Seasonal Affective Disorder (SAD), a type of mood disorder that is more common during the winter months. SAD is characterized by symptoms such as increased appetite, sluggishness, and increased sleepiness, and it affects up to 10% of the population in some areas.
The role of melatonin in SAD is significant. Melatonin is a hormone that regulates sleep-wake cycles, and its production is affected by the amount of light exposure. Reduced daylight during winter can disrupt melatonin levels, contributing to the symptoms of SAD. A possible non-drug therapy for SAD is light therapy, which involves exposure to artificial light that mimics natural light, helping to adjust melatonin production and alleviate the depressive symptoms associated with this disorder.
Major depressive disorder is a complex illness with potential genetic and environmental contributions. While the exact causes of major depression are unclear, some theories suggest changes in neurotransmitter levels such as norepinephrine, serotonin, and possibly dopamine might play a role. Treatments for depression vary and may include psychotherapy, antidepressant medications, and light therapy, especially in cases of SAD.