Winter Blues: Seasonal Affective Disorder (SAD)
Seasonal Affective Disorder (SAD)

Seasonal Affective Disorder (SAD)

Depression can occur at any time of year. However, for many, winter represents the most vulnerable time. Changes in sunlight, temperature, changes in the brain and body’s internal chemistry, and the stress of the Holidays can all play a role. In some ways, Winter Depression is built into our biology – just think of bears that hibernate during the winter. Indeed, symptoms of winter depression can mimic hibernation, with lack of energy, sleepiness with difficulty getting out of bed, and an increased appetite with carb-cravings. Difficulty with concentration and focus can also be a symptom. Because of the physical symptoms, some describe seasonal affective disorder (SAD) as “vegging out.”

Some individuals only experience depression during the winter while others may experience it any time of year but more so during the winter.

Some specific findings associated with winter depression include:

1) Lower available levels of the brain chemical messenger serotonin. There is evidence that serotonin remains less available to stimulate neurons for people with SAD. This is because after serotonin is released from a neuron, thereby making it available to attach to and activate docking stations (known as receptors) on surrounding neurons, it is sucked back in by the releasing neuron too quickly in people with Seasonal Affective Disorder (SAD).

2) People with SAD may make too much melatonin, a hormone that promotes sleepiness. Excess melatonin levels can cause daytime fatigue. This can also throw off a person’s day-night cycle (circadian rhythm).

3) Insufficient Vitamin D levels may play a role in SAD. Vitamin D may be involved in the action of serotonin.

4) Activity of a structure deep in the brain called the hypothalamus may be uniquely sensitive to sunlight in people with SAD. The Hypothalamus controls sleep and appetite, and also may play a role in mood.

Treatment for Seasonal Affective Disorder (SAD):

First, it is important to rule out other possible causes, such as low thyroid or anemia as examples. I have had a number of patients where these were uncovered as causes of fatigue.

Very effective treatment for SAD is available. Bright Light therapy, Cognitive-Behavioral Therapy (CBT), and antidepressants are the most evidence-based. These and others that are often helpful are listed below.

Bright Light therapy

There are lots of different styles and price points of bright light lamps or boxes. Specific levels of luminosity (often 10,000 lux is recommended) and timing of bright light are important components. The timing of bright light may depend on the type of depression. For pure SAD or winter worsening of depression, the morning is usually best. Morning bright light resets circadian rhythm, activates the hypothalamus, and suppresses melatonin secretion. Melatonin release is regulated by light. Melatonin is always primed to be released in the brain but held back or suppressed by bright light. This is why melatonin is released at night (and also why you shouldn’t bring your phone or laptop into bed at night!).
(Note that although using bright light later in the day can make SAD worse by messing up circadian rhythm, there are always exceptions. I occasionally find that bright light later in the day whether exclusively or in addition to morning light paradoxically is more beneficial. Also, mid-day bright light is better for Bipolar depression).


Many antidepressants are used for winter depression but one is specifically FDA approved for it. However, your doctor needs to make sure this is the right antidepressant for you (for example, it’s not as good for some symptoms of depression or anxiety).

Cognitive-Behavioral therapy (CBT)

This can help change unhelpful behaviors and negative thinking, help change perspectives on the winter, and teach stress-reduction techniques.

Exercise. For those who are not inclined towards exercise, thinking of this recommendation simply as “getting the blood flowing” can be helpful, as even 10 minutes of physical activity a day can be beneficial. Outdoor activities can be especially helpful.

Vitamin D. Consult your doctor for Vitamin D dosing for SAD.

This article was originally published on Dr. Neal Ranen, Baltimore Psychiatric Services