One such prominent condition is Seasonal Affective Disorder (SAD), a specific subtype of MDD. This disorder unveils its symptoms primarily during the shift in seasons, notably fall and winter, when daylight hours are shorter. People with SAD experience symptoms such as low energy, irritability, difficulty concentrating, changes in sleep patterns, and a persistent feeling of sadness.
SAD and seasonal depression are terms often used interchangeably, but they represent distinct concepts. SAD is a specific subtype of major depressive disorder characterised by its seasonal pattern of recurring depressive episodes that occur during particular seasons, commonly fall and winter; however, spring-onset depression exists, too. Seasonal depression, on the other hand, is a more general term that can encompass various mood disorders or depressive symptoms that occur seasonally, not necessarily meeting the specific diagnostic criteria for SAD. Both conditions share a connection to environmental factors, but SAD is a more narrowly defined clinical diagnosis within the broader category of seasonal affective changes.
The exact cause of SAD is not fully understood. However, it is believed to be linked to a lack of sunlight exposure, which can affect the body's internal clock and disrupt the balance of certain neurotransmitters in the brain. SAD, as compared to seasonal depression, is more pervasive, lasts longer, and requires the presentation of more symptoms of depression to be diagnosed.