What is Seasonal Affective Disorder (SAD) and what are my treatment options?

Seasonal Affective Disorder

What is Seasonal Affective Disorder (SAD) and what are my treatment options?

Seasonal Affective Disorder

Many people find themselves feeling down during the dark and dreary winter months. For some, the winter blues become serious depression. Seasonal affective disorder (SAD) is a pattern of major depressive episodes, with symptoms typically occurring each year during the fall and winter. Dr. Norman E. Rosenthal and colleagues first described SAD at America’s National Institute of Mental Health in 19841. The causes of SAD are still not entirely clear.

It is important to distinguish between the ‘winter blues’ and SAD. People with SAD suffer notable dysfunction as their energy levels plunge. People with the winter blues are able to manage basic demands of life, although with difficulty.

You may have SAD if you experienced these symptoms seasonally for the past 2 years:
• Increased need for sleep (hypersomnia).
• Difficulty waking from sleep.
• Feeling tired during the day.
• Problems concentrating, especially in the afternoon and evening.
• Increased appetite and carbohydrate cravings; or loss of appetite.
• Unintentional weight-gain; or weight-loss.
• Social withdrawal.
• Irritability.
• Feeling ‘down’ or depressed.
• Feelings of worthlessness, shame, or guilt.
• Loss of interest in normal activities.
• Decreased libido.
• Suicidal thoughts.

Seasonal affective disorder can also affect people during warmer seasons. Over 1/3 of SAD sufferers experience mild hypermania in the spring and summer (excessive excitability, enthusiasm, talkativeness, decreased need for sleep).

The prevalence of SAD varies, with ranges typically reported from 0-10% in different populations. Geographical location, ethnicity, skin tone, and gender all influence susceptibility to SAD2. Women of reproductive age comprise up to 60-90% of reported cases.

If you think you have SAD, speak to your doctor as treatment should be monitored by a licensed medical professional. Some treatment options for SAD include:

Light Therapy

Light therapy uses special boxes, known as lightboxes, which mimic outdoor light. Patients are instructed to sit in front of the lightbox daily, usually in the morning, for about 20-30 minutes. Researchers believe light therapy induces chemical changes in the brain that can boost mood and ease other SAD symptoms.

All lightboxes are designed do the same thing, but some may work better than others. Keep in mind that lightboxes are not regulated by Health Canada or the Food and Drug Administration (FDA).

A lightbox should:
• Provide 10,000 lux of light.
• Provide the full spectrum of bright light except UV rays (the lightbox should block out 99% of UV rays).

You can purchase a lightbox without a prescription, but it is best to talk to your doctor before you buy one. Light therapy can have side effects including: headaches, eye strain, irritability, and insomnia. Increasing exposure too fast or for too long can induce manic episodes in people who also have bipolar disorder.

Although research shows that light therapy for SAD treatment is effective3,4, nearly half of those treated do not get better. Light therapy may be more effective when combined with another SAD treatment, such as cognitive-behavioural therapy, exercise, or an antidepressant.

Cognitive-Behavioural Therapy (CBT)

Cognitive-behavioral therapy for SAD teaches coping skills and helps change thought patterns. Overall, CBT may be more effective than light therapy alone.

Researchers at the University of Vermont compared CBT and light therapy in a randomised study of 177 adult participants with SAD5. Half of participants were given six-weeks of CBT, and the other half six-weeks of light therapy. While both light therapy and CBT were equally effective short-term, participants who received CBT were less likely to experience a relapse of SAD in the long-term (27.3 per cent of CBT participants relapsed during the second winter, compared with 45.6 per cent of light therapy participants).

One of the reasons why CBT is more effective long-term may be due to a lack of consistency in lightbox users. Less than 1/3 of light therapy participants continued treatment one or two winters later6.


Exercise has long been a treatment option for depression, including SAD. Heading outside during daylight hours can make a difference. A study comparing the effects of one week of light therapy vs daily exercise sessions, found exercise and light therapy to have a similar effect in reducing depression symptoms7. In addition to reducing depression, SAD individuals who exercised also boosted their metabolisms.

Vitamin D

Vitamin D is normally produced in the body from exposure to ultraviolet light, and production dips in the winter. Low levels of vitamin D are associated with depression, as vitamin D plays an important role in making the brain chemicals dopamine and serotonin. For this reason, Vitamin D supplements are sometimes used to treat depression and data supports a beneficial effect8.

Researchers believe that the amount of vitamin D matters. Improvement in SAD symptoms only occurs with higher doses (at least 100 micrograms daily). Studies using lower doses of vitamin D found the supplements did not make a difference9.


Antidepressant treatment can help SAD when nothing else is working. Sometimes light therapy, CBT, and lifestyle changes aren’t enough. Traditionally, selective serotonin reuptake inhibitors (SSRIs), a class of antidepressant, are prescribed for seasonal affective disorder. Research shows that SSRIs fluoxetine (Prozac) and sertraline (Zoloft) help SAD sufferers10, 11, but the data is limited and conflicting. A different type of antidepressant, bupropion (Zyban), has also shown promise for SAD treatment12.

Perhaps more important is the timing of antidepressant treatment. Dr. Rosenthal and colleagues found that patients who started the antidepressant bupropion-XL before the onset of SAD symptoms (during the fall) had a lower recurrence of depression, and reduced their risk by 44 per cent13.

As with all antidepressants, there are side effects. It is important to be informed before starting any antidepressant treatment. Common side effects can include weight-gain, nausea, diarrhea, insomnia, and dry mouth.

If you are considering antidepressant treatment, Pillcheck can help. Pillcheck measures your unique drug metabolism and recommends optimal medications. Using Pillcheck to choose an antidepressant can reduce the risk of adverse side effects.

You should share your Pillcheck report and the pharmacist’s opinion letter with your doctor – that’s the best way to make use of the recommendations.

Visit www.pillcheck.ca to learn more.


  1. Rosenthal NE, et al. Seasonal affective disorder. A description of the syndrome and preliminary findings with light therapy. Arch Gen Psychiatry. 1984. 41(1):72-80.
  2. Rosenthal NE. Winter blues: everything you need to know to beat seasonal affective disorder. New York, NY: Guilford Press; 2006.
  3. Mårtensson B, Pettersson A, Berglund L, & Ekselius L. Bright white light therapy in depression: A critical review of the evidence. Journal of affective disorders. 2015. 182, 1-7
  4. Nussbaumer B, et al. Light therapy for preventing seasonal affective disorder. The Cochrane database of systematic reviews. 2015. 11
  5. Rohan K, et al. Randomized Trial of Cognitive-Behavioral Therapy Versus Light Therapy for Seasonal Affective Disorder: Acute Outcomes American Journal of Psychiatry. 2015. 172 (9), 862-869.
  6. Rohan K, et al. Outcomes One and Two Winters Following Cognitive-Behavioral Therapy or Light Therapy for Seasonal Affective Disorder. The American journal of psychiatry. 2015.
  7. Partonen T, et al. Randomized trial of physical exercise alone or combined with bright light on mood and health-related quality of life. Psychol Med. 1998. 28:1359–64.
  8. Spedding, S. Vitamin D and Depression: A Systematic Review and Meta-Analysis Comparing Studies with and without Biological Flaws. Nutrients. 2014. 6(4): 1501–1518.
  9. Frandsen T, et al. Vitamin D supplementation for treatment of seasonal affective symptoms in healthcare professionals: a double-blind randomised placebo-controlled trial. BMC Research Notes. 2014. 7 (1)
  10. Partonen T, Lonnqvist J. Moclobemide and fluoxetine in treatment of seasonal affective disorder. J Affect Disord. 1996. 41:93–9.
  11. Moscovitch A, et al. A placebo-controlled study of sertraline in the treatment of outpatients with seasonal affective disorder. Psychopharmacology. 2004. 171:390–7.
  12. Niemegeers P, et al. Bupropion for the treatment of seasonal affective disorder Expert Opinion on Drug Metabolism & Toxicology. 2013. 1-12
  13. Modell JG, et al. Seasonal affective disorder and its prevention by anticipatory treatment with bupropion XL. Biol Psychiatry. 2005. 58(8):658-67.


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