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Seasonal Affective Disorder

What is seasonal affective disorder?

Seasonal affective disorder (SAD) is a type of mood disorder that presents with similar symptoms to anxiety and depression, with the difference that these symptoms are related to changes in seasons. SAD typically has an onset in the fall months, symptoms peak in the winter months, and recover by the end of spring. The most common symptoms are moodiness, lack of energy, and oversleeping. Though most people will feel some difference in mood between the summer and winter months, if this change in mood is causing a change in quality of life and enjoyment of daily activities, it could be due to SAD. Many are unaware of the existence of SAD and might try to tough it out on their own, without seeking the appropriate help.

Symptoms of SAD

In most cases, SAD symptoms appear during the long nights of late fall or early winter and go away during the sunnier days of spring and summer. Less commonly, people with the opposite pattern have symptoms that begin in spring or summer. In either case, symptoms may start out mild and become more severe as the season progresses. A particularly cold winter could cause more severe symptoms in people with SAD.

General signs and symptoms of SAD may include:

  • Feeling depressed most of the day, nearly every day
  • Losing interest in activities you once enjoyed
  • Having problems with sleeping
  • Experiencing changes in your appetite or weight
  • Feeling sluggish or agitated
  • Having difficulty concentrating

Symptoms specific to SAD related to the fall and winter months, sometimes called winter depression, may include:

  • Oversleeping
  • Craving for foods high in carbohydrates
  • Weight gain
  • Tiredness or low energy

Symptoms specific to SAD related to the spring and summer months, sometimes called summer depression, may include:

It is normal to have some days when you feel down. However, if these feelings persist for several days at a time and hurt your motivation to do activities you would otherwise enjoy, make an appointment to see your doctor. This is especially important if you are also noticing changes to patters in your sleep or appetite.


The specific causes of SAD are not well understood, although some of the factors that come into play include:

  • Your circadian rhythm, also known as your biological clock. Reduced level of sunlight and vitamin D in fall and winter may cause winter-onset SAD. This decrease in sunlight may disrupt your body’s internal clock and lead to feelings of depression. This is especially meaningful for people living in northern communities such as Canada that are particularly affected by shortened days and lowered temperatures.
  • Serotonin levels. Reduced exposure to sunlight can also cause a drop in serotonin, an important brain chemical that affects our mood. Lowered levels of serotonin are known to cause depression, and a seasonal drop in serotonin could trigger SAD.
  • Melatonin levels. The change in season can affect the body’s production of melatonin, a hormone responsible for regulating sleep patterns. This shift in melatonin can cause sleep to not be restful, resulting in oversleeping while not recovering from feelings of tiredness.

Risk factors

In general, women are more likely than men to be diagnosed with SAD. It also occurs more frequently in younger adults than in older adults.

Other factors that may increase your risk of SAD include:

  • Family history. Although there is no direct genetic component, many mood disorders tend to have an increased incidence in people with relatives suffering from similar conditions.
  • Having other mood disorders. Symptoms of depression may worsen seasonally if you are diagnosed with major depression, generalized anxiety, or bipolar disorder.
  • Living far from the equator. As mentioned before, shorter days cause less exposure to sunlight, and living far from the equator exposes people to these conditions. This is likely due to the large variation in length of days between the winter and summer.


SAD treatments fall into three categories: phototherapy, psychotherapy, and medications.

  1. Phototherapy – Phototherapy is the use of exposure to light at specific wavelengths. In the case of SAD, it has been shown that phototherapy makes up for lost exposure to sunlight and helps return the body’s biological clock back to its baseline. Studies show that phototherapy can improve the harmful symptoms of SAD, lasting a month after each treatment. It is also preferred to medication due to not having any harmful side effects.
  2. Psychotherapy – Similar to other mood disorders, cognitive behavioural therapy (CBT), group therapy and other forms of counselling can help the individual understand their feelings of depression and work through them effectively. This type of treatment can be used alone or in conjunction with others.
  3. Medications – Antidepressants are effective treatments for SAD, and are generally as effective as light therapy. For those people where phototherapy is ineffective, antidepressants should be considered upon the consultation with a medical doctor.


Signs and symptoms of SAD should be taken seriously. As with any other mood disorder, SAD can get worse and lead to problems if it’s not treated. These can include:

  • Social withdrawal
  • School or work problems
  • Substance abuse
  • Other mental health disorders such as anxiety or eating disorders
  • Suicidal thoughts or behaviour

Treatment can help prevent complications, especially if SAD is diagnosed and treated before symptoms get bad.


CAMH. (2020). Seasonal affective disorder (SAD).
Retrieved from: https://www.camh.ca/en/health-info/mental-illness-and-addiction-index/seasonal-affective-disorder

If you have any questions or client issues regarding this article or its contents, feel free to reach out directly to Rx Infinity or contact us here at ASSOCIUM and we will facilitate the connection or you. If your issue or question is specific to your personal and prescribed medication, please contact your physician or your providing pharmacy.

This information is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health provider with any questions about your medical condition. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.

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