Seasonal Affective Disorder

What is Seasonal Affective Disorder?

Seasonal Affective Disorder (SAD), also known as seasonal depression, is a form of depression that is triggered by changes in the seasons. SAD is most commonly triggered during the late autumn, when the days become shorter and the weather gets colder, lasting until the warmer days of spring. Although it is normal to feel a little melancholy during the colder months, SAD has a more severe impact on individuals, impacting their daily life and behaviour. Rarely, some individuals may experience SAD with a reverse seasonal pattern, feeling depression symptoms during the late spring into early autumn.

SAD does not impact all individuals equally. It is more common for women and younger individuals to experience SAD. Additionally, individuals with mood disorders, or those living in cloudy, more overcast areas of the world, are at a greater risk of experiencing SAD.

What are the symptoms?

Individuals with SAD may experience:

  • Feelings of sadness and depression almost every day
  • Feeling anxious
  • Oversleeping and/or extreme fatigue
  • Weight gain
  • Increase or changes in appetite (eg, greater cravings for carbohydrates)
  • Feelings of hopelessness or worthlessness
  • Difficulty concentrating
  • Feelings of irritability
  • Loss of interest in activities previously enjoyed
  • Disruptions in sleep patterns
  • Thoughts of self-harm

Individuals with summer (reverse) SAD may experience:

  • Insomnia
  • Feeling anxious
  • Feelings of irritability or agitation
  • Loss of appetite and/or weight loss
What are the causes?

While it is not exactly certain what causes SAD, there are factors believed to contribute to the disorder, including;

  • Changes in your biological clock (circadian rhythm). The decreased amount of sunlight during the colder months may disrupt your body’s internal clock and cause the onset of SAD.
  • Changes in serotonin levels. Serotonin is a neurotransmitter that influences your mood. The decreased amount of sunlight during late fall may cause a drop in serotonin, leading to feelings of depression.
  • Vitamin D deficiency. Vitamin D helps boost your serotonin levels, contributing to a more positive mood. In the winter months, the lack of sunlight can decrease vitamin D production, which may cause a worsened mood. 
  • Changes in melatonin levels. Melatonin is a hormone that your body produces in response to darkness and helps maintain your circadian rhythm. Melatonin may be overproduced during the colder months, causing fatigue in some individuals.
What are the treatment options?

If you think you might have SAD, seek help form a mental health professional. There are a variety of treatments available to minimize the symptoms of SAD, including:

  • Light therapy (phototherapy). This is the primary treatment option for individuals experiencing SAD. Light therapy uses a special lamp called a lamp box that can mimic natural light, and help minimize the affects of SAD.
  • Cognitive Behavioural Therapy (CBT). CBT is a type of talk therapy that can help manage feelings of depression or anxiety.
  • Antidepressant medication. Medication is sometimes recommended to manage feelings of depression and is often used in tandem with light therapy.
  • Spending time outdoors. Getting outside more frequently may decrease the effects of SAD. Additionally, increasing the amount of sunlight that enters your home or workspace can help to manage SAD symptoms.
  • Vitamin D Supplements. Taking vitamin D supplements during the colder months can help to increase serotonin levels, which in turn may improve SAD symptoms. If you already take medication, consult your doctor before starting vitamin D supplements, as they may interact with other prescription or over-the-counter medications.