Seasonal Mood Swings: A Forty-Year Journey

Forty years ago, the term Seasonal Affective Disorder (SAD) was coined. Today, it’s known as a specific kind of mood disorder. In the American Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-V), seasonality is listed as a specifier for both recurrent depression and Major Depressive Disorder (MDD), as well as Bipolar Disorder (BD). Winter depression is the most common form of SAD. Its symptoms, like excessive sleepiness and carb cravings, mirror atypical depression. Up to 20% of people with MDD or BD can experience SAD, and it's more common in women. SAD is a severe example of how the central nervous system (CNS) reacts to the annual changes in light. These changes affect hormones like melatonin, neurotransmitters like dopamine and serotonin, and the hypothalamic-pituitary-adrenal axis. "Clock genes" play a vital role in these daily and yearly processes. Some researchers suggest that SAD might be a remnant from our Neanderthal ancestors. Light therapies, such as bright light therapy (BLT) and blue light, are effective treatments for winter depression. Dawn simulation methods also help. Interestingly, light restriction using blue light blocking glasses shows promising results in managing manic states.