Seasonal Affective Disorder
Introduction & Clinical Features
Seasonal affective disorder (SAD) is a type of depressive disorder characterized by episodes of depression at certain times of the year. SAD should not be confused with SADS (sudden arrhythmia death syndrome), a generic heart condition that can cause sudden death in apparently healthy young people.
SAD diagnoses are usually made by qualified health professionals using criteria from the Diagnostic and Statistical Manual of Mental Disorder (DSM-IV-TR; American Psychiatric Association, 2000). Most episodes begin in fall or winter and remit (go away) in the spring.
According to the DSM-IV-TR, Seasonal Affective Disorder (SAD) involves a pattern of seasonal onset of at least two depressive episodes with remissions, and no nonseasonal depressive episodes, that have occurred during the past two years. Also, seasonal depressive episodes must outnumber nonseasonal episodes over the person’s lifetime.
With SAD, seasonal depression cannot be better explained by psychosocial stressors such as unemployment during the winter months or a seasonal school schedule (American Psychiatric Association, 2000). SAD can range from mild dysphoria (feeling unwell or unhappy) to severe depression. In addition to sadness or depressed mood, SAD symptoms include lack of energy, hypersomnia (sleeping a lot), overreacting, weight gain, and carbohydrate cravings. Major depressive disorder or bipolar episodes (usually bipolar II) may be seasonal in nature.
There are high rates of SAD among adults with attention-deficit hyperactivity disorder (ADHD)Opens in new window. If an individual has seasonal bipolar disorder, full-spectrum light therapy (phototherapy) may cause switching to manic or hypomanic episodes.
SAD occurs more frequently in women and at higher latitudes (close to the North pole). Winter depressive episodes occur more in younger people. SAD is also seen in individuals who work at night or do shift work, and in areas with significant cloud cover or pollution that blocks out sunlight (Preston, O’Neal, & Talaga, 2008). SAD is thought to occur by lack of exposure to bright light, and because of deficits of the neurotransmitter (chemical messenger) serotonin.
Effective treatments include full-spectrum intensive light therapy (phototherapy) and medications. Light therapy involves exposure to light of a specified intensity and type for a prescribed duration (dosage), often at a specific time of day.
Since the serotonin system is thought to be involved, antidepressant medications prescribed are usually selective serotonin reuptake inhibitors (SSRIs, e.g., Prozac) or monoamine oxidase inhibitors. Melatonin (N-acetyl-5-methozytryptamine, a hormone extracted from the pineal gland) has been tried as an alternative (complementary) treatment for SAD but has not been found to be effective in relieving depressive symptoms (Putiloy & Danilenko, 2005).
- American Psychiatric Association. (2000), Diagnostic and statistical manual of mental disorders (4th ed., text rev.). Washington, DC: Author.
- Preston, J.D., O’Neal, J. H., & Talaga, M.C. (2008). Handbook of clinical psychopharmacology for therapists (5th ed.). Oakland, CA: New Harbinger.
- Putilov, A.A., & Danilenko, K.V. (2005). Antidepressant effects of combination of sleep deprivation and early evening treatment with melatonin or placebo for winter depression. Biological Rhythm Research, 36, 389 – 403.
- Rybak, Y.E., McNeely, H.E., MacKenzie, B.E., Jain, U.R., & Levitan, R.D. (2007). Seasonality and circadian preference in adult attention-deficit/hyperactivity disorder: Clinical and neuropsychological correlates. Comprehensive Psychiatry, 48, 562 – 571.