Seasonal affective disorder (SAD) is a type of depression that comes and goes with the seasons. It usually starts in the late fall and early winter and goes away during the spring and summer. Some people do have episodes of depression that start in the spring or summer, but that is a lot less common. Symptoms of SAD may include:
- Sadness
- Gloomy outlook
- Feeling hopeless, worthless, and irritable
- Loss of interest or pleasure in activities you used to enjoy
- Low energy
- Difficulty sleeping or oversleeping
- Carbohydrate cravings and weight gain
- Thoughts of death or suicide
SAD is more common in women, young people, and those who live far from the equator. You are also more likely to have SAD if you or your family members have depression.

The exact causes of SAD are unknown. Researchers have found that people with SAD may have an imbalance of serotonin, a brain chemical that affects your mood. Their bodies also make too much melatonin, a hormone that regulates sleep, and not enough vitamin D.
The main treatment for SAD is light therapy. The idea behind light therapy is to replace the sunshine that you miss during the fall and winter months. You sit in front of a light therapy box every morning to get daily exposure to bright, artificial light. But some people with SAD do not respond to light therapy alone. Antidepressant medicines and talk therapy can reduce SAD symptoms, either alone or combined with light therapy.
I want to add a note from personal experience to this discussion. I took care of my aunt who suffered and died from Alzheimer’s Disease for the last six years of her life. We had always been close and spoke nearly daily on the phone for the years prior to her being diagnosed with the disease One of the things we had discussed was her getting ‘depressed’ in the winter time when the days got short. As I was acquainted with SAD, I feared that she might suffer far more in the winter when it combined with her Alzheimer’s Disease. So, I bought some full spectrum lights for her apartment. These are used in light therapy and unlike regular lights which give a yellow glow, they broadcast the entire spectrum of light – replicating sunlight. So, my aunt was able to have the equivalent of summer daylight in her home during winter’s darkest hours. She never sank into a depression in the years I took care of her. So, light therapy can be effective.
Tony