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What is Seasonal Affective Disorder?

Seasonal Affective Disorder, or SAD for short, is a mood/affect disorder that occurs during a particular season of the year resulting in variable degrees of impairment as implied by the name.  

SAD is not considered a separate mood disorder, rather, it is considered a subtype of well-defined mood disorders such as major depressive disorder, Bipolar I disorder, and Bipolar II disorder. As such, patient with SAD can experience depression, mania, or hypomania.


Who gets SAD and why?

In population-based studies, the lifetime prevalence of SAD is 0.5-3%. The most prevalent form is winter depression that typically begins in late fall and remits by the spring time. As such, it is possible that some cases of the "Holiday Blues" associated with Christmas are actually cases of SAD. The presence of a preexisting mood disorder account for no more than 30% of cases of SAD.

The age of onset of SAD is typically between 20-30 years of age. Though no clear risk factors have been established, SAD tends to be more prevalent among women and among adults (with lower rates amongst children, adolescents, and elderly patients). Another observation that is not well established is that people residing at higher northern latitudes where daylight is scarce are at increased risk.

The reason why SAD occurs is not known. Several proposed theories have been put forth however including a disruption in the circadian rhythm (sleep-wake cycles), reduced retinal sensitivity, genetic factors, dysregulation of Serotonin (the "feel good" chemical), or a combination of these thoughts.

Symptoms of SAD:

As mentioned above, the most prevalent form of SAD is a depressive episode, especially during the winter months. However, this is not the only pattern that exists. Below is a discussion of the two most common SAD episodes and associated symptoms.

  • Winter depression (fall-winter onset):

  1. Episodes are characterized by increased sleep, increased appetite, carbohydrate craving, and weight gain. Most episodes resolve by spring and for sure summer time.

  • Summer depression (spring-summer onset):

  1. Episodes re characterized by typical symptoms of depression which include depressed mood, insomnia, decreased need for sleep, decreased appetite, and weight loss.

Other symptoms of depression can accompany these periods and include anhedonia (loss of pleasure or interest), fatigue, cognitive dysfunction, psychomotor slowing, feelings of guilt, worthlessness, and suicidal thoughts/behavior. SAD can often be comorbid with Attention Deficit and Hyperactivity Disorder (ADHD), alcohol use disorder, binge eating disorder, panic disorder, generalized anxiety disorder, social anxiety disorder, and premenstrual dysmorphic disorder.

Diagnosis of SAD:

The diagnosis of SAD is purely clinical and done according to the Diagnostic and Statistical Manuel or Mental Disorders (DSM-5). The latter defines this entity as recurrent episodes of depression, mania, or hypomania with seasonal onset and remission. Patients have to clearly demonstrate a cyclical pattern of mood changes in relation to a particular season and resolution thereafter. If symptoms persist beyond said season, then a primary mood disorder (such as Major Depressive Disorder or Bipolar disorder) or an underlying medical condition (such as thyroid dysfunction) should be suspected and investigated.

Treatment of SAD:

The treatment of SAD largely depends on illness severity. Severe illness is defined as having seven to nine depression symptoms as discussed above on a nearly daily basis and resulting in significant impairment in daily function. Mild to moderate illness on the other hand is defined as having six or less depression symptoms that result in manageable impairment that is not obvious to others.

The treatment of SAD includes lifestyle modification, therapy sessions, pharmacologic intervention, or a combination of the above. Starting a medication is largely dependent on the severity of illness and degree of impairment but should always be a discussion between the provider and the patient.

The three main treatments are light therapy, psychotherapy, and an antidepressant/mood stabilizer. If exposure to natural light is not possible or adequate (such as the northern hemisphere or night workers), use of artificial light therapy is recommended first. This may be done in isolation or combined with antidepressant or mood stabilizers that are typically used in primary mood disorders. Should that fail, then psychotherapy, particularly Cognitive Behavioral Therapy (CBT), should be offered with a trained and boarded psychologist.

In addition to these treatment modalities, lifestyle changes can often be added to supplement treatment and increase success rate. Such changes include practicing proper sleep hygiene as set forth by the American Academy of Sleep, daily walking, aerobic exercise, and meditation. 

Oliver Achi, MD

Medical Director of Neurology Services

Iberia Medical Center


If you or a loved one suffer from depression or bipolar disorder including SAD with prior suicidal tendencies, please go to the nearest emergency room or contact the Louisiana Suicide and Crisis Lifeline at 988. 

The Iberia Medical Center Neurology clinic wishes you all a very Merry Christmas and a Happy New Year!!!

Seasonal Affective Disorder

Dec 16, 2022

Iberia Medical Center

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