Seasonal affective disorder

(Redirected from Seasonal Affective Disorder)
Jump to: navigation, search

For patient information click here

Seasonal affective disorder
Bright light lamp.jpg
Light therapy lamp for the treatment of seasonal affective disorder (SAD)

WikiDoc Resources for Seasonal affective disorder


Most recent articles on Seasonal affective disorder

Most cited articles on Seasonal affective disorder

Review articles on Seasonal affective disorder

Articles on Seasonal affective disorder in N Eng J Med, Lancet, BMJ


Powerpoint slides on Seasonal affective disorder

Images of Seasonal affective disorder

Photos of Seasonal affective disorder

Podcasts & MP3s on Seasonal affective disorder

Videos on Seasonal affective disorder

Evidence Based Medicine

Cochrane Collaboration on Seasonal affective disorder

Bandolier on Seasonal affective disorder

TRIP on Seasonal affective disorder

Clinical Trials

Ongoing Trials on Seasonal affective disorder at Clinical

Trial results on Seasonal affective disorder

Clinical Trials on Seasonal affective disorder at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Seasonal affective disorder

NICE Guidance on Seasonal affective disorder


FDA on Seasonal affective disorder

CDC on Seasonal affective disorder


Books on Seasonal affective disorder


Seasonal affective disorder in the news

Be alerted to news on Seasonal affective disorder

News trends on Seasonal affective disorder


Blogs on Seasonal affective disorder


Definitions of Seasonal affective disorder

Patient Resources / Community

Patient resources on Seasonal affective disorder

Discussion groups on Seasonal affective disorder

Patient Handouts on Seasonal affective disorder

Directions to Hospitals Treating Seasonal affective disorder

Risk calculators and risk factors for Seasonal affective disorder

Healthcare Provider Resources

Symptoms of Seasonal affective disorder

Causes & Risk Factors for Seasonal affective disorder

Diagnostic studies for Seasonal affective disorder

Treatment of Seasonal affective disorder

Continuing Medical Education (CME)

CME Programs on Seasonal affective disorder


Seasonal affective disorder en Espanol

Seasonal affective disorder en Francais


Seasonal affective disorder in the Marketplace

Patents on Seasonal affective disorder

Experimental / Informatics

List of terms related to Seasonal affective disorder

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Haleigh Williams, B.S.

Synonyms and Keywords: SAD; seasonal disorder; seasonal depression; winter blues; winter depression


Seasonal affective disorder (SAD), also known as winter depression, is a form of depression that is correlated with changes in the season. In the most common form of SAD, an individual experiences more frequent depressive periods between the late fall and early spring, with no such instances in the late spring and summer months. Less commonly, patients may experience depressive episodes in the summer; this type of disorder is often referred to as reverse seasonal affective disorder.[1][2][3]

Historical Perspective

SAD was first described during the 1980s by South African physician Normal Rosenthal, who noticed that he felt significantly less industrious and energetic during the winters following his move to the United States, though he returned to his normal state during the spring.[2]


Rather than being defined as its own distinct disorder, SAD is classified as a specific type of depression that involves a persistent association between depressive episodes and seasonal changes.[1][3]


Though the physiological basis of SAD is not completely clear, people with SAD seem to suffer from some of the following hormonal/neurotransmitter imbalances more frequently than the general population:[1][2]

  • Serotonin. Studies have shown that individuals suffering from winter-occurring SAD produce more serotonin transporter protein in the winter months than in the summer months, which means serotonin has less of an effect.
  • Melatonin. In the winter, as days become shorter and periods of darkness lengthen, the production of melatonin increases. This can interfere with a patient’s circadian rhythm and induce lethargy and drowsiness.
  • Vitamin D. Patients with SAD tend to have lower levels of vitamin D than their unaffected counterparts; this deficiency may play a role in exacerbating depression through interference with the action of serotonin.

Commonly co-morbid conditions include:[4]


The cause of SAD has not yet been determined, though both genetic and environmental factors appear to play a role.[1][2]

Differentiating seasonal affective disorder from other diseases

SAD must be differentiated from diseases that present with similar symptoms, including:[1][4]

Epidemiology and Demographics

The prevalence of SAD ranges from 1.5% to 9%, depending on latitude.[5]


SAD is most commonly diagnosed in young adults.[2]


SAD is more common in women than in men. Women are four times as likely as men to be diagnosed with SAD.[2]


No racial predilection for SAD has been observed.

Risk Factors

Risk factors for SAD include:[1][2]

  • Being female
  • Living far from the equator
    • SAD is particularly prevalent at latitudes in the Arctic region, such as Finland (64º 00´N), where the rate of SAD is 9.5%.[6] Cloud cover may contribute to the negative effects of SAD.[7]
  • Having a family history of any type of depression
  • Being a young adult


No formal screening guidelines exist for SAD. The Seasonal Pattern Assessment Questionnaire (SPAQ), developed by Rosenthal in 1984, is an effective, self-administered tool for patients who think they might be suffering from SAD.[2]

Natural History, Complications, and Prognosis

  • The age of onset of SAD is generally between 18 and 30 years.[2]
  • SAD can be a serious disorder and may necessitate hospitalization.[7]
    • There is also potential risk of suicide in some patients experiencing SAD.
    • One study reports 6-35% of sufferers required hospitalization during one period of illness.
    • The symptoms of SAD mimic those of dysthymia or clinical depression.
  • With treatment, the prognosis of SAD is generally good, though some people with SAD continue to experience the full effects of the disorder throughout their lives.[8]


Diagnostic Criteria

A diagnosis of SAD is appropriate for patients who meet all of the criteria for a diagnosis of major depression and in whom the incidence of depression has been observed to correspond to the onset of specific seasons for a period of no less than two years.[1][3]


General symptoms of major depression include:[1]

  • Feeling depressed a majority of the time
  • Feeling hopeless or insignificant
  • Lethargy
  • Losing interest in activities one previously enjoyed
  • Having trouble sleeping
  • Experiences changes in appetite or weight
  • Having difficulty concentrating
  • Having frequent thoughts of death or suicide

Symptoms of winter-occurring SAD include:[1][2]

Symptoms of summer-occurring SAD include:[1][2]

Physical Examination

There is no formal, established test for SAD. A diagnosis is made by asking a patient about his/her history of symptoms.[8]

Laboratory Findings

Though no laboratory findings are diagnostic of SAD, a healthcare professional may need to perform blood tests to rule out other disorders that present with similar symptomology.[8]

Imaging Findings

No imaging findings are associated with SAD.

Other Diagnostic Studies

No other diagnostic modalities are associated with SAD.


Medical Therapy

  • Options for the treatment of SAD include medication, light therapy, psychotherapy, and the administration of vitamin D.
  • Any of these therapies may be used on its own or in combination with another.[1]


Light Therapy

  • SAD has been treated primarily with light therapy, also referred to as bright light therapy (BLT) or phototherapy, since the 1980s.[1][2]
    • The rationale behind the use of light therapy is that the depressive effect of decreased sunlight during the late fall and winter months can be counteracted through daily exposure to bright light.
    • Patients who undergo light therapy typically use a light box each morning from early fall until the start of spring.
    • The use of light boxes generally calls for between 20 and 60 minutes of exposure to 10,000 lux of cool-white fluorescent light, which is approximately 20 times greater in brightness than standard lighting.
  • As evidence of the efficacy of light therapy as compared to other treatment options is far from conclusive, experts recommend that decisions about forms of treatment be guided greatly by the preferences of individual patients.[5]
  • Common side effects of light therapy include eye strain and headaches.[8]
  • Light therapy is contraindicated for individuals on photosensitizing medications.[2]


  • The use of psychotherapy, specifically cognitive behavioral therapy (CBT), to treat SAD is common.[1]
    • CBT helps patients recognize and replace depressing thoughts.
    • Patients are also encouraged to engage in activities they find pleasing and engaging as a technique for coping with their symptoms.

Vitamin D

  • Though the administration of vitamin D has not been proven to be an effective treatment for SAD, researchers have postulated that it may be helpful due to decreased vitamin D levels observed in SAD patients.[1]
    • Studies intended to determine the efficacy of vitamin D as a treatment for SAD have yielded mixed results.


Surgery is not recommended for the management of SAD.


  • There are no established measures for the primary prevention of SAD.
  • Measures for the secondary prevention of SAD include:[8]
    • Getting an adequate amount of sleep
    • Eating a healthy, balanced diet
    • Taking medicine as directed
    • Exercising regularly
    • Avoiding alcohol and illegal drugs


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 National Institute of Mental Health. “Seasonal Affective Disorder.” 2016.
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 Melrose S (2015). "Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches.". Depress Res Treat. 2015: 178564. PMC 4673349Freely accessible. PMID 26688752. doi:10.1155/2015/178564. 
  3. 3.0 3.1 3.2 Diagnostic and statistical manual of mental disorders : DSM-5. Washington, D.C: American Psychiatric Association. 2013. ISBN 0890425558. 
  4. 4.0 4.1 Lurie SJ, Gawinski B, Pierce D, Rousseau SJ (2006). "Seasonal affective disorder.". Am Fam Physician. 74 (9): 1521–4. PMID 17111890. 
  5. 5.0 5.1 Nussbaumer B, Kaminski-Hartenthaler A, Forneris CA, Morgan LC, Sonis JH, Gaynes BN; et al. (2015). "Light therapy for preventing seasonal affective disorder.". Cochrane Database Syst Rev (11): CD011269. PMID 26558494. doi:10.1002/14651858.CD011269.pub2. 
  6. Avery, D H (2001). "Dawn simulation and bright light in the treatment of SAD: a controlled study". Biological Psychiatry. 50 (3): 205–216 = id = 11513820. Retrieved 2007-05-05. 
  7. 7.0 7.1 Modell, Jack (2005). "Seasonal affective disorder and its prevention by anticipatory treatment with bupropion XL Biological Psychiatry". 58 (8): 658–667. 16271314. 
  8. 8.0 8.1 8.2 8.3 8.4 U.S. National Library of Medicine. MedlinePlus. “Seasonal affective disorder.” 2016.
  9. U.S. National Library of Medicine. MedlinePlus. “Bupropion.” 2016.
  10. U.S. National Library of Medicine. MedlinePlus. “Sertraline.” 2016.