What is Seasonal Affective Disorder?

According to Johns Hopkins Medicine, Seasonal affective disorder, or SAD, is a type of depression. It happens during certain seasons of the year—most often fall or winter. It is thought that shorter days and less daylight may trigger a chemical change in the brain leading to symptoms of depression. Light therapy and antidepressants can help treat SAD.

The National Institute of Mental Health (NIMH) stated that many people go through short periods of time where they feel sad or not like their usual selves. Sometimes, these mood changes begin and end when the seasons change. People may start to feel “down” when the days get shorter in the fall and winter (also called “winter blues”) and begin to feel better in the spring, with longer daylight hours. In some cases, these mood changes are more severe and can affect how a person feels, thinks, and handles daily activities. If you have noticed significant changes in your mood and behavior whenever the seasons change, you may be suffering from seasonal affective disorder (SAD). In most cases, SAD symptoms start in the late fall or early winter and go away during the spring and summer; this is known as winter-pattern SAD or winter depression. Some people may experience depressive episodes during the spring and summer months; this is called summer-pattern SAD or summer depression and is less common.

Who is at Risk for SAD?

SAD usually starts during adulthood. The risk of SAD increases with age. It’s rare in people under age 20. Women are affected more often than men.

What causes Seasonal Affective Disorder ?

Scientists do not fully understand what causes SAD. Research indicates that people with SAD may have reduced activity of the brain chemical (neurotransmitter) serotonin, which helps regulate mood. Research also suggests that sunlight controls the levels of molecules that help maintain normal serotonin levels, but in people with SAD, this regulation does not function properly, resulting in decreased serotonin levels in the winter. Other findings suggest that people with SAD produce too much melatonin—a hormone that is central to maintaining the normal sleep-wake cycle. Overproduction of melatonin can increase sleepiness. Both serotonin and melatonin help maintain the body’s daily rhythm which is tied to the seasonal night-day cycle. In people with SAD, the changes in serotonin and melatonin levels disrupt normal daily rhythms. As a result, they can no longer adjust to the seasonal changes in day length, leading to sleep, mood, and behavior changes. Deficits in vitamin D may exacerbate these problems because vitamin D is believed to promote serotonin activity. In addition to vitamin D consumed with diet, the body produces vitamin D when exposed to sunlight on the skin. With less daylight in the winter, people with SAD may have lower vitamin D levels, which may further hinder serotonin activity. Negative thoughts and feelings about the winter and its associated limitations and stresses are common among people with SAD (as well as others). It is unclear whether these are “causes” or “effects” of the mood disorder, but they can be a useful focus of treatment.

What are the Symptoms of SAD?

There are two types of SAD:

  1. Fall-onset. This is also called “winter depression.” Symptoms of depression begin in the late fall to early winter months and ease during the summer months.
  2. Spring-onset. This is also called “summer depression.” Symptoms of depression begin in late spring to early summer. This type is much less common.

The following are the most common symptoms of SAD:

  • Increased sleep and daytime drowsiness
  • Loss of interest and pleasure in activities formerly enjoyed
  • Social withdrawal and increased sensitivity to rejection
  • Irritability and anxiety
  • Feelings of guilt and hopelessness
  • Fatigue, or low energy level
  • Decreased sex drive
  • Decreased ability to focus or concentrate
  • Trouble thinking clearly
  • Increased appetite, especially for sweets and carbohydrates
  • Weight gain
  • Physical problems, such as headaches

Symptoms tend to come back and then improve at about the same times every year. The symptoms of SAD may look like other mental health conditions. Always see a healthcare provider for a diagnosis.

How is Seasonal Affective Disorder diagnosed?

Depression often happens with other conditions, such as heart disease or cancer. It may also happen with other mood disorders, such as substance abuse or anxiety. For these reasons, early diagnosis and treatment is key to recovery. A diagnosis of SAD may be made after a careful mental health exam and medical history done by a psychiatrist, psychologist, or other mental health professional.

How is SAD treated?

The treatments for “winter depression” and “summer depression” often differ, and may include any, or a combination, of the following:

  • Exposure to sunlight. Spending time outside or near a window can help relieve symptoms.
  • Light therapy. If increasing sunlight is not possible, exposure to a special light for a specific amount of time each day may help.
  • Cognitive-behavioral or interpersonal therapy helps change the distorted views you may have of yourself and the environment around you. It can help you improve interpersonal relationship skills and identify things that cause you to stress as well as how to manage them.
  • These prescription medicines can help correct the chemical imbalance that may lead to SAD.

There are also things you can do for yourself to help relieve symptoms:

  • Get help. If you think you may be depressed, see a healthcare provider as soon as possible.
  • Set realistic goals considering depression. Don’t take on too much. Break large tasks into small ones, set priorities, and do what you can as you can.
  • Try to be with other people and confide in someone. It is usually better than being alone and secretive.
  • Do things that make you feel better. Going to a movie, gardening, or taking part in religious, social, or other activities may help. Doing something nice for someone else can also help you feel better.
  • Get regular exercise.
  • Expect your mood to get better slowly, not right away. Feeling better takes time.
  • Eat healthy, well-balanced meals.
  • Stay away from alcohol and drugs. These can make depression worse.
  • Delay big decisions until the depression has lifted. Before deciding to make a significant transition—change jobs, get married or divorced—discuss it with others who know you well and have a more objective view of your situation.
  • Remember: People rarely “snap out of” depression. But they can feel a little better day by day.
  • Try to be patient and focus on the positives. This may help replace the negative thinking that is part of the depression. The negative thoughts will disappear as your depression responds to treatment.
  • Let your family and friends help you.

Key points about SAD

  • SAD is a type of depression that happens during a certain season of the year—most often in fall and winter.
  • There is no clear cause of SAD. Less sunlight and shorter days are thought to be linked to a chemical change in the brain and may be part of the cause of the seasonal affective disorder (SAD). Melatonin, a sleep-related hormone, also may be linked to SAD.
  • In general, nearly everyone with depression has ongoing feelings of sadness and may feel helpless, hopeless, and irritable.
  • SAD may be diagnosed after a careful mental health exam and medical history done by a psychiatrist, psychologist, or other mental health professional.
  • Depression is most often treated with light therapy, psychotherapy, and in some cases antidepressants.