What to Do When You’re Feeling Blue

Treatments for Seasonal Affective Disorder

February 1, 2020

As sunlight decreases and long, dark days drag on, the winter blues begin to settle like a dead weight. Waking up in the morning becomes harder and harder, arms feel too heavy to lift the once-light household items like vacuums and brooms, and waves of sleepiness and fatigue are almost overpowering all day long.

“SAD is a type of depression that comes and goes with the seasons.”

Seasonal affective disorder (SAD) is recurrent major depression that follows a seasonal pattern. It is most commonly present during the autumn or winter months, with full remission in other seasons. Less commonly, SAD can cause depression during the spring and summer months. It’s considered a type of depression that comes and goes with the seasons and is not classified as a separate disorder. [i]  

In general, SAD is characterized by low energy and a sad mood. Symptoms of SAD vary but can include: Hypersomnia, increased appetite, carbohydrate cravings, feelings of hopelessness, thoughts of suicide, weight gain, fatigue, difficulty concentrating, irritability, and social situation avoidance. [ii, iii] Symptoms of major depression can be present: feelings of guilt, loss of interest or pleasure in activities usually enjoyed, or sustained feelings of hopelessness. Additionally, SAD symptoms typically reoccur about the same time each year and are not related to obvious seasonal stressors, such as holiday expenses or higher utility bills during the winter. [ii] Summer onset seasonal affective disorder symptoms can include: insomnia, poor appetite, agitation, and/or weight loss. [iv] A SAD diagnosis is based on meeting the DSM-5 criteria of major depression coinciding with specific seasons for at least two years. Typically, seasonal affective disorder depressive symptoms are mild to moderate, but for some they can disable daily functioning. [ii]

What causes seasonal affective disorder?

Although we do not know the exact causes of SAD, several key biological clues can help us understand the condition and potential treatments.

Serotonin Production

Individuals with SAD may have trouble regulating serotonin, a neurotransmitter involved with balancing mood. [v] In one study, people with SAD had five percent more serotonin transporter proteins in winter months than in the summer. However, more serotonin transporter proteins result in lower serotonin activity and can result in depression [vi]. During the summer, sunlight keeps serotonin transporter protein levels low, but as sunlight diminishes, there is a corresponding decrease in serotonin activity. [v]

Melatonin Production

SAD may also be associated overproduction of melatonin, a hormone produced in the presence of darkness by the pineal gland that causes sleepiness [v]. As daylight diminishes in the winter, melatonin production increases and individuals with SAD feel lethargic and sleepy. [v] However, “Although melatonin likely plays a role in impacting the symptoms of SAD, it cannot by itself account for these phenomena.” [v]

Circadian Rhythm And Vitamin D

Both serotonin and melatonin are intimately involved with circadian rhythm, the body’s 24-hour, light-dark, sleep-wake body clock. Decreased serotonin and increased melatonin influence the body’s circadian rhythm. With less outdoor activity in the presence of sunlight exposure, the body produces less vitamin D. “Vitamin D is believed to play a role in serotonin activity, Vitamin D deficiency and insufficiency have been associated with clinically significant depressive symptoms.” [v] Although there is not yet evidence that shows causation of SAD from serotonin, melatonin, circadian rhythms, and vitamin D, these are all key areas that seem to be influencing SAD and are still being researched.

Who is at risk?

About 10 million Americans experience seasonal affective disorder each year and another 10 – 20% may have mild SAD. [ii] Amongst Canadians, 15% experience mild SAD and two to six percent experience SAD. [v] In the United Kingdom, around two percent of the population suffers from SAD while 20% experience mild SAD. [v] Those at greatest risk for SAD are young females, living far from the equator, and having a family history of depression, bipolar disorder, or seasonal affective disorder. [v] Women have four times the risk of SAD than men. It is estimated that age of onset of SAD is between 18 and 30 years old. [ii]  

What treatment options are available?

There are two main treatments aimed at increasing serotonin production.


Medication can play a role in the treatment of mental health disorders and conditions. Selective Serotonin Reuptake Inhibitors (SSRIs), such as Prozac or Wellbutrin, among other medications such as antidepressants, are commonly employed to treat SAD. SSRIs enhance the activity of serotonin by blocking its reuptake into the neuron. While antidepressants can effectively treat depression, they come with side effects, such as nausea, headache, dizziness, dry mouth, agitation, weight change, etc. It can take several different medications to find one that improves symptoms without causing adverse side effects. [i] Medications have their time and place, but there are also other treatments free from potentially harmful side effects to consider and bring to your healthcare professional’s attention if they have not already discussed them with you.  

Many people are understandably concerned about the side effects of medication and ask if there are natural ways to boost serotonin for the brain. The answer is yes.

Light Therapy

Light therapy or phototherapy has been a foundational SAD treatment since the 1980s. Light therapy increases exposure to bright light which stimulates serotonin production. Use of a lightbox first thing in the morning for 30 – 60 minutes each day from early fall to spring may relieve SAD symptoms. [v, vii] Light therapy increases blood serotonin, making it more available to the brain. [iii]

One study found that immediate mood improvements can be noted after the first exposure of light for as short as 20 minutes, but that 40 to 60 minutes of exposure produced even greater improvement. [vii] Light box or light therapy glasses filter out UV rays and most studies are of 10,000 lux cool-white light (20 times brighter than household lighting). [i] However, light therapy research shows that blue light therapy with lower intensity lux is just as effective as 10,000 lux white light therapy [viii] and does not have the increased risk of macular degeneration and cataracts.  

Nedley Health offers hands-free light glasses. Used properly, light therapy is free from side effects. When possible, exposure to bright, natural light throughout the day is also important.

Other treatments that are not related to increasing serotonin in the brain include psychotherapy and maintaining healthy levels of vitamin D.


Cognitive Behavioral Therapy is effective in SAD treatment. An adaptation utilized is called CBT-SAD. “CBT-SAD relies on basic techniques of CBT such as identifying negative thoughts and replacing them with more positive thoughts along with a technique called behavioral activation. Behavioral activation seeks to help the person identify activities that are engaging and pleasurable, whether indoors or outdoors, to improve coping with winter.” [i]

A randomized control trial conducted by the University of Vermont followed 177 participants. Study subjects qualified for SAD diagnosis were tracked prospectively for six weeks of CBT-SAD or light therapy treatment through two winters. There was no statistically significant difference between treatments the first year; however, after the second winter, “CBT-SAD was associated with fewer recurrences at the second winter than light therapy, more remissions at the second winter using BDI-II criteria, and significantly decreased depression scores.” [ix] The study concluded, “CBT-SAD should be considered as an efficacious SAD treatment and disseminated into practice, particularly if the focus is on recurrence prevention.” [ix]

Learn more about CBT here. CBT is also free from side effects and can be combined with other treatments for SAD.

Vitamin D

Vitamin D levels are often very low among individuals suffering from SAD, due to insufficient sun exposure and dietary intake. [i] There is mixed research on the effectiveness of vitamin D as a SAD treatment, but improving vitamin D levels favorably impacts depression. [x]


These various treatments are often used in combination, especially when one treatment has not been effective in reducing SAD symptoms.

It is important to plan self-care as a part of your treatment of SAD. Taking conscientious effort with the following activities can help you cope with seasonal depression:

  • Take advantage of any available sunlight
  • Plan activities that you enjoy during winter
  • Engage in physical activity
  • Monitor your mood and energy levels
  • Seek help for your condition when symptoms develop
  • Approach winter with a positive attitude [ii]

There are other factors that can play a role in the treatment and prevention of seasonal affective disorder. Eating a diet rich in nutrients for building neurotransmitters can help. Identifying and setting appropriate winter goals can help as well. Do not be afraid to reach out for help. Learn more about whether or not you have depression and gain tools to climb out of seasonal affective disorder. Get to know your mood and take action to combat SAD before the symptoms begin.

“You deserve to enjoy life, even in the wintertime.”

If you are putting off getting help because you are busy, believe others need help more than you, or that you’ll just wait until the spring to feel better again, it’s time for you to reconsider. There is nothing selfish about prioritizing your own wellbeing. Investing in yourself is worth both the time and money (like purchasing a light box). When you are happier, others are happier too. Remember, you deserve to enjoy life, even in the wintertime.

Please contact us first before publishing this or other Let’s Talk Mental Health articles.


[i] Seasonal Affective Disorder. (2016). NIMH. Retrieved January 28, 2020.

[ii] Seasonal Affective Disorder. (n.d.). Retrieved January 22, 2020.

[iii] Nørgaard, M., Ganz, M., Svarer, C., Fisher, P. M., et al. (2017). Brain Networks Implicated in Seasonal Affective Disorder: A Neuroimaging PET Study of the Serotonin Transporter. Frontiers in neuroscience, 11, 614. doi:10.3389/fnins.2017.00614

[iv] Seasonal affective disorder (SAD). (2017). Retrieved January 28, 2020, from https://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/symptoms-causes/syc-20364651

[v] Melrose S. (2015). Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches. Depression research and treatment, 2015, 178564. doi:10.1155/2015/178564

[vi] Mc Mahon, Brenda, Andersen, Sofie B., et al. [2014]. Patients with seasonal affective disorder show seasonal fluctuations in their cerebral serotonin transporter binding. European Neuropsychopharmacology. 2014;24(supplement 2):p. S319.doi: 10.1016/s0924-977x(14)70506-1.

[vii] Virk, G., Reeves, G., Rosenthal, N. E., Sher, L., & Postolache, T. T. (2009). Short exposure to light treatment improves depression scores in patients with seasonal affective disorder: A brief report. International journal on disability and human development : IJDHD, 8(3), 283–286. doi:10.1901/jaba.2009.8-283  

[viii] Meesters, Y., Winthorst, W. H., Duijzer, W. B., & Hommes, V. (2016). The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder. BMC psychiatry, 16, 27. doi:10.1186/s12888-016-0729-5

[ix] Rohan, K. J., Meyerhoff, J., Ho, S.-Y., Evans, M., Postolache, T. T., & Vacek, P. M. (2016). Outcomes One and Two Winters Following Cognitive-Behavioral Therapy or Light Therapy for Seasonal Affective Disorder. American Journal of Psychiatry, 173(3), 244–251. doi: 10.1176/appi.ajp.2015.15060773  

[x] Vellekkatt, F., & Menon, V. (2019). Efficacy of vitamin D supplementation in major depression: A meta-analysis of randomized controlled trials. Journal of postgraduate medicine, 65(2), 74–80. doi:10.4103/jpgm.JPGM_571_17

About the author


Cami Martin, MPH, is the Health Education Director for Nedley Health Solutions. She is an international trainer for the community-based health education program Optimize Your Brain™ and the 8-week Nedley Depression & Anxiety Recovery Program™. Her passion is disseminating information on living a mentally healthy lifestyle to people around the world. Cami works closely with all NHS programs to continually enhance and expand each program.