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Seasonal Affective Disorder

4 min read · 3 sections

Seasonal affective disorder, or SAD, is a form of depression that affects some people at about the same time each year, usually beginning in the late fall or early winter and dissipating in the spring or summer.1 SAD is associated with biochemical brain changes that occur with decreased sunlight and changes to a person’s internal clock (also known as their circadian rhythm).2

People sometimes minimize SAD, thinking it is just the normal feeling of being a little down in the winter when it’s cold and difficult to spend a lot of time enjoying the outside. However, SAD is more than that and can be so severe as to impair a person’s day-to-day functioning.2

Per the American Psychiatric Association, about 5% of adults in the U.S. suffer from seasonal affective disorder, and they usually experience symptoms roughly 40% of the year; however, SAD occurs less often in people who live in places with more hours of sunlight in the winter. Generally, the farther one lives from the equator, the more likely they are to develop SAD. According to one study, less than 2% of people surveyed in Florida experienced SAD, as opposed to almost 10% of those surveyed who lived in New Hampshire.3

According to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), SAD is not a separate disorder but rather a type of major depressive disorder, called major depressive disorder with seasonal pattern. Thus, the individual must meet the normal criteria for major depressive disorder. Furthermore, the episodes must correlate with certain seasons and must fully remit during the rest of the year. This pattern needs to have occurred twice in the last 2 years and there cannot be any other depressive episodes during that period. Lastly, over the course of the individual’s lifetime, there must be markedly more seasonal episodes must than nonseasonal episodes.4


Symptoms of major depression may include:1

  • Depressed mood.
  • Feeling hopeless.
  • Feeling worthless.
  • Lack of interest in previously enjoyed activities.
  • Lethargy and increased fatigue.
  • Agitation of sluggishness.
  • Problems concentrating.
  • Sleep problems.
  • Changes in appetite or significant, unintentional changes in weight.
  • Suicidal thoughts or attempt(s).

Rarely, SAD episodes occur during the summer months, although it is much more common during the cold, dark months of late fall, winter, and early spring. Whether the person experiences SAD episodes during the winter or summer months makes certain symptoms more likely. Those who suffer from SAD episodes in the colder seasons may be more prone to:1

  • Sleeping too much.
  • Lack of energy.
  • Overeating and weight gain.
  • Craving carbs.
  • Withdrawing socially or “hibernating”.

Individuals impacted by SAD episodes in the warmer months may be more prone to:1

  • Eating less than normal and losing weight.
  • Problems sleeping.
  • Agitation.
  • Anxiety.
  • Violent outbursts.

Risk Factors

In addition to living farther from the equator, other factors that can play a role in the likelihood that someone will develop seasonal affective disorder may include:1,2

  • Age: SAD can affect people of any age, but it is more common to start in younger adults. SAD is most likely to first appear when an individual is between the ages of 18 and 30, although even children and teens are sometimes affected.
  • Gender: Females are more likely to be diagnosed. In fact, women are diagnosed with SAD 4 times more often than men.
  • Family History: Those with family members who’ve suffered from any kind of depression are more likely to develop SAD.
  • Existing mood disorders: In people with depression or bipolar disorder, depressive symptoms may worsen with the seasons. However, SAD is only diagnosed if the seasonal depressive episodes notably outnumber nonseasonal episodes.

Causes of SAD

Although the precise cause of seasonal affective disorder is unknown, there are three main factors that seem to be involved, all of which are or may be related to the changing nature of the environment due to seasonal cycles.1,5

  • Lower availability of serotonin: Serotonin is one of the brain’s neurotransmitters, and it is thought to be responsible in part for feelings of wellbeing and happiness. Additionally, an article in Innovations in Clinical Neuroscience reports that human skin might have the ability to generate serotonin, which may be stimulated by exposure to sunlight. With shorter days in winter, less exposure to sunlight could mean less serotonin, leading to symptoms of depression. Another study found that people who suffer from SAD have slightly more serotonin transporters in winter months than in the summer, leaving less of the neurotransmitter available at the synapse.
  • Increased levels of melatonin: Melatonin is a hormone that helps to regulate sleep and wake cycles. It is produced in higher levels in darkness, so one’s level of melatonin will rise during winter months. This can lead to oversleeping or a lack of daytime energy. People with SAD may overproduce this hormone.
  • Underproduction of Vitamin D: Vitamin D may be linked to serotonin activity. With an inadequate amount of the vitamin, depressive symptoms may arise. Vitamin D is produced when sunlight transforms a chemical in a person’s skin, so production can decrease in the dark winter months.6

The Relationship between SAD and Substance Abuse

When the dark days come, and the symptoms of SAD present themselves, some people may self-medicate with substances. A lack of energy may cause some to turn to stimulants. Others may seek to numb the pain of depression with drugs like opioids or alcohol. Research has shown that some individuals with alcoholism misuse alcohol seasonally, so they may be self-medicating SAD.7

Self-medicating with substances may lead to addiction. Additionally, the use of alcohol and drugs may worsen the symptoms of SAD,so while self-medicating may feel like it’s effective in the moment, it may worsen depressive symptoms overall and set the person on a path to a substance use disorder.

Per the Anxiety and Depression Association of America, about 20% of Americans with an anxiety or mood disorder, such as SAD, also struggle with a substance use disorder, and vice versa.9 According to the National Institute on Drug Abuse, approximately 50% of all people who struggle with a mental health disorder will also experience a substance use disorder at some point.10

Treatment Options

If someone suffers from both SAD and a substance use disorder, both conditions should be treated simultaneously.10 If only the addiction is addressed, the untreated seasonal affective disorder may trigger a relapse back to substance abuse, and an untreated substance use disorder may worsen depressive symptoms. For individuals with both mental illness(es) and substance use disorder(s), integrated treatment that addresses all psychiatric disorders provides better results.11

Psychotherapy can be useful for both substance use disorders and seasonal affective disorder. For example, cognitive behavioral therapy (CBT) may be a core part of treatment for both disorders.1,10

Treatment for seasonal affective disorders fall into three main areas: phototherapy, psychotherapy, and medication.


Since seasonal affective disorder is believed to be related to a reduction in exposure to sunlight, the first line of treatment is often increased exposure to light, or phototherapy. While many studies on the effects of phototherapy do not have a clinically rigorous design due to the challenges of creating a placebo, “multiple systematic reviews and meta-analyses evaluating the available data support the use of light therapy as an effective treatment for SAD,” according to American Family Physician.12

Phototherapy involves sitting, usually for at least 20 minutes a day, in front of a light therapy box that emits bright light but filters out the UV rays.2

In some countries that sit at more northern latitudes, communities are experimenting with novel approaches to light therapy. In Rjukan, Norway, the town has installed three large rotating mirrors on one of the two mountains that tower over Rjukan. The mirrors reflect the sunlight into the town square, where residents can gather in winter months to soak up the rays. In Umeå, Sweden, the school Dragonskolan has installed full spectrum lamps in several of the classrooms, bathing the students in light, with the goal of improving student attendance and performance.

Some companies have created small light sources using LED bulbs for at-home treatment. A study of the effectiveness of one such product for the treatment of SAD has shown promising results.13

Phototherapy is unlikely to be available in a substance abuse treatment program. However, many are located in sunnier climates, which could be beneficial for individuals with SAD, especially if they make a point to regularly spend some time outdoors. Additionally, the options listed below often are available at addiction treatment centers.

Cognitive Behavioral Therapy

Cognitive behavioral therapy (CBT) is a form of therapy that helps an individual change harmful thoughts, beliefs, and behaviors into more accurate and functional ones, which can improve his or her mood. CBT can be a helpful treatment for depression, trauma-related disorders, anxiety, substance use disorders, and more.14,15 One study found that a type of CBT specifically for SAD had better effects on those who suffer from SAD the second winter after acute treatment than light therapy did.16


Selective serotonin reuptake inhibitors (SSRIs), a type of antidepressant, are sometimes prescribed for SAD.2 These drugs can increase the amount of available serotonin in the brain by preventing cells from reabsorbing serotonin.17

Ways to Support Treatment for SAD

While anyone who thinks they may have SAD should seek professional treatment, there are some things you can do to help relieve symptoms.8,12

  • Get outside. Aim to get more natural sunlight.
  • Open the blinds. Try to get more sunlight in your home and work environments as well, opening up the blinds and shades to let the maximum amount of light in.
  • Eat a balanced diet. Although more research is needed, eating a diet high in vegetables, fruits, and fish may decrease the likelihood of feeling depressed.18
  • Get moving. Several studies have indicated that exercise may be beneficial for individuals with SAD.19
  • Seek out support. Lean on friends and family when possible. Seasonal affective disorder often leaves people with the urge to withdraw socially, but it’s usually better to spend time with others and let them help you. Having a trusted loved one to talk to may help improve your mood.

It is common to feel a reduction in energy and change in mood during the winter months, but if your mood is affecting your ability to take pleasure in life, or you feel like you don’t have the energy to get through your day, or if you are suffering or struggling in other ways, talk to a medical professional about seasonal affective disorder. If you are misusing drugs or alcohol to alleviate your symptoms and you can’t stop, don’t wait to get help. Treatment programs exist that treat comorbid substance use and mood disorders.


  1. National Institute of Mental Health. (2016). Seasonal Affective Disorder.
  2. American Psychiatric Association. (2017). Season Affective Disorder (SAD).
  3. Roecklein, K. A., & Rohan, K. J. (2005). Seasonal affective disorder: an overview and update. Psychiatry (Edgmont (Pa. : Township)), 2(1), 20-6.
  4. American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders: Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Arlington, VA: American Psychiatric Association, 2013
  5. Sansone, R. A., & Sansone, L. A. (2013). Sunshine, serotonin, and skin: a partial explanation for seasonal patterns in psychopathology?. Innovations in clinical neuroscience, 10(7-8), 20-4.
  6. Mayo Clinic. (2017). Vitamin D.
  7. Sher, L. (2004). Alcoholism and seasonal affective disorder. Comprehensive Psychiatry, 45(1), 51-56.
  8. University of Rochester Medical Center. (n.d.) Seasonal Affective Disorder or SAD.
  9. Anxiety and Depression Association of America. (n.d.). Substance Use Disorders.
  10. National Institute on Drug Abuse. (2018). Comorbidity: Substance Use Disorders and Other Mental Illnesses.
  11. Kelly, T. M., & Daley, D. C. (2013). Integrated treatment of substance use and psychiatric disorders. Social work in public health, 28(3-4), 388-406.
  12. Kurlansik, S. & Ibay, A. (2013). Seasonal Affective Disorder. Indian Journal of Clinical Practice, 24(7).
  13. Desan, P., et al. (2007). A controlled trial of the Litebook light-emitting diode (LED) light therapy device for treatment of Seasonal Affective Disorder (SAD). BMC Psychiatry, 7(38).
  14. American Psychiatric Association. (2016, July). What is Psychotherapy?
  15. McHugh, R. K., Hearon, B. A., & Otto, M. W. (2010). Cognitive behavioral therapy for substance use disorders. The Psychiatric clinics of North America, 33(3), 511-25.
  16. Rohan, K. J., Meyerhoff, J., Ho, S. Y., Evans, M., Postolache, T. T., & Vacek, P. M. (2015). Outcomes One and Two Winters Following Cognitive-Behavioral Therapy or Light Therapy for Seasonal Affective Disorder. The American journal of psychiatry, 173(3), 244-51.
  17. Mayo Clinic. (2018). Selective serotonin reuptake inhibitors (SSRIs).
  18. Zeratsky, K. (2018). Junk food blues: Are depression and diet related?
  19. Peiser, B. (2009). Seasonal affective disorder and exercise treatment: a review. Biological Rhythm Research, 40(1), 85-97.
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