As a psychologist who closely monitors all aspects of my patients’ well-being, over the years I have realized that our environment drastically impacts our moods. Working with my long-term patients, I have learned that depression for some of my clients begins around Thanksgiving, gets worse up to New Year’s Day, and suddenly improves by the end of winter. Some people’s stress levels might increase during the holiday season, which in turn might trigger depression. However, the patients I am referring to struggle with a different type of depression during this season, known as seasonal depression disorder.

Seasonal depression or, as it is known to psychologists, seasonal affective disorder, is a mental health disorder which affects 5% of the population in the United States. Researchers have found that 15.6% to 38% of patients who seek mental health counseling for depression meet the criteria for this disorder. Studies confirm that women are more susceptible than men by a ratio of 4 to 1.

I first met Mary (not her real name) when she came for counseling last year around December. Mary was 28 years old and had been happily married for 20 years. She had two young children. She told me that for the past few weeks, she had been feeling dead inside. She complained about a lack of energy and feeling sadness all the time.

She was feeling guilty because she did have the desire or energy to partake in her family’s festivities and hated to “steal” their joy. She locked herself in her bedroom, crying for hours, after she dropped her children off at school in the morning. She couldn’t make sense of her depression, because nothing had changed in her life over the past few months. She told me that this had become a familiar pattern for her over the past five years.

We graphed the changes in her mood and it was clear to me that she was struggling with seasonal depression. Mary was surprised to learn how much her mood depended on the changes of the season. With this new realization and learning effective tools to manage her disorder, she was able to put an end to this dreadful cycle.

Symptoms of Seasonal Depression

Although there are many similarities between major depressive disorder and seasonal depression, there are a few signifiers that differentiate them from each other. The main difference is that individuals with seasonal depression experience a temporal pattern in their depressive symptoms, showing a relationship with changes in the seasons. Though many report feeling depressed in the winter and feeling better during spring and summer, there are some individuals who experience the opposite pattern.

Below you will find a list of some common symptoms that individuals with seasonal depression might experience:

• Feeling tired all the time and excessive sleepiness (hypersomnia)
• Increased appetite and weight gain
• Helplessness and hopelessness
• Defeated demeanor
• Issues with concentration, forgetfulness, and negative thoughts about winter

Given that feeling sluggish, overeating, and weight gain are among the symptoms of this disorder, many of sufferers are misdiagnosed and their disorder is labeled a “non-specific medical condition.” 

Causes of Seasonal Depression

Scientists have researched various possible causes for the development of seasonal depression. The study of hundreds of brain scans highlighted changes in the serotonin transporter (SERT) protein in individuals who struggle with seasonal depression. Elevated amounts of serotonin transporter protein in winter lead to a greater removal of serotonin in this population during this season. Serotonin is a chemical produced in our body to keep our mood balanced, and a lack of serotonin is often correlated with depressive mood.

The phase-shift hypothesis notes that the biological clocks of individuals with seasonal depressive disorder runs more slowly during the winter due to the changes in light. Melatonin is a chemical in our body that monitors our sleep. The later dawn in winter does not provide enough time for the amount of melatonin in our blood to drop, and our body may feel that it is still nighttime. According to this theory, delays in one’s circadian rhythm, the daily biological rhythms that regulate sleepiness and wakefulness, might be responsible for the out-of-sync feeling in individuals with seasonal depression.

Although there remain several different possible explanations for seasonal depression, research has found promising avenues for its treatment. In most cases, light therapy, psychotherapy, and medication significantly alleviate seasonal depression’s symptoms and provide effective tools to overcome this frustrating condition.