Seasonal Affective Disorder (abbreviated SAD) is a form of depression characterized by recurrent episodes of major depression, typically occurring right in the middle of the holiday season. This disorder manifests in a distinct pattern, with symptoms improving during the spring and summer months, only to make a resurgence in the fall and winter. 

The main theory is that a lack of sunlight might affect the function of the hypothalamus, which in turn may affect the: 

• production of melatonin. Melatonin is a hormone that makes you feel sleepy. In people with SAD, the body may produce higher than normal levels. 

• production of serotonin. Serotonin is a hormone that affects your mood, appetite and sleep. A lack of sunlight may lead to lower serotonin levels, which is linked to feelings of depression.

• the circadian rhythm. Our bodies use sunlight to time various functions, like waking up. Lower light levels during winter may disrupt your body's internal clock and lead to symptoms of SAD.

cause vitamin D deficiency. Vitamin D is believed to promote serotonin activity. The body produces vitamin D when exposed to sunlight on the skin, in addition to obtaining vitamin D from food sources.  With less daylight in the winter, people may have lower vitamin D levels. which in turn reduces serotonin activity.

Treatments are available to help people with Seasonal Affective Disorder.  These fall into four main categories that can be used alone or in combination. 

• light therapy

• psychotherapy, specifically cognitive behavior therapy

• antidepressant medications

• vitamin D supplementation

• lifestyle Measures: adequate exposure to natural light, even on overcast days is encouraged. Regular physical activity, maintaining a consistent sleep schedule, and having a well balanced diet contributes to overall well-being. Staying active and connected, such as volunteering, getting together with friends and family and participating in group activities can also help manage the symptoms of SAD.

Just as with other forms of depression, it is important to make sure there are no other medical conditions that could be causing your symptoms. SAD can be misdiagnosed in the presence of hypothyroidism, hypoglycemia and some types of viral infections, so a proper evaluation is important. Talk to your health care provider to discuss the symptoms and treatments for this manageable condition.