If you have ever noticed that you feel fatigued, cranky, and generally down from November through late February, you may be suffering from a mild form of seasonal affective disorder (SAD). According to Marla Ahlgrimm, SAD is a type of depression that is triggered by the time change of the winter months. As the sun begins to set - sometimes as early as 4 PM - we have less daylight. Less daylight means less energy. Why?
Marla Ahlgrimm explains that the summer sun means more exposure to sunlight. This leads your brain to producing more serotonin. This hormone, which is closely intertwined with our moods, dips when it is darker for longer. This can leave us feeling like a shell of ourselves and longing for spring. 
Marla Ahlgrimm notes that this mood change is not only related to the lack of serotonin. People tend to get tired in the dark because our ancestors used that as a trigger for sleep. Although we have lights 100% of the time now, our bodies have yet to evolve to stay awake in the nighttime hours.
Symptoms of SAD include pulling away from friends and family, uncontrolled fatigue, increased hunger, and extreme anxiety. Marla Ahlgrimm says that only about 2% of the population experiences true seasonal affective disorder, but the vast majority of us are affected in some way by longer nights and shorter days.
If you experience unsettling mood changes in the winter, Marla Ahlgrimm suggests changing your diet, getting enough sleep, and exercising. The combination of these three healthful activities may give your brain just enough of a boost to overcome the negative consequences of an early-dimming sky.
