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  • Writer's pictureMarjorie DeStefano, PMHNP-BC

Feeling SAD? Seasonal Affective Disorder Explained

Spring is just a few weeks away, and for those who suffer from seasonal changes in mood, the promise of longer, warmer days may also represent hope for a brighter mood.


People commonly think of seasonal affective disorder (SAD) as the “winter blues” or depression that occurs in winter months. In fact, Seasonal affective disorder (SAD) is more general term to describe either mania or depression, that correspond with a transition in season (Avery, 2020a). According to the DSM V (2013), seasonal affective disorder is not an official psychiatric diagnosis. Rather, “with seasonal pattern” is a specifier used for either major depression or bipolar disorders, where depressive or manic episodes correlate to changes of season. Others may suffer from “subsyndromal SAD,” meaning they do not meet criteria for a diagnosis of depression or bipolar disorder but do exhibit distinct changes in mood occurring in a seasonal pattern (Avery, 2020b).


SAD encompasses changes in mood in a person with an existing mood disorder, either onset of mania or depressive episodes, which occur seasonally in the transition from spring to summer or from fall to winter. The prevalence of a fall/winter onset is so much greater than that of the spring/summer onset, 3% compared to 0.1%, (Avery, 2020a). Women are affected in a 4:1 ratio compared to men, and younger people tend to be affected more commonly than older people (Meesters & Gordijn, 2016). Interestingly, seasonal changes in mood do not always recur in those who have experienced them in the past. In fact, studies have determined that 25-50% of people will not experience recurrent symptoms from winter to winter (Avery, 2020a).


In addition to typical depressive symptoms that might occur during a major depressive episode or bipolar depressive episode, such as decreased interest in enjoyable activities, loss of energy, problems with concentration, feelings of guilt and worthlessness, and thoughts of death and/or suicide, those with seasonal affective disorder with fall/winter onset tend to experience increased appetite, carbohydrate cravings, weight gain, and increased need for sleep. Conversely, those with a spring/summer onset tend to experience decreased appetite, weight loss, and insomnia (Avery, 2020a).


In theory, SAD occurs as a result of physiological changes that occur due to seasonal changes in sunlight exposure, including dysregulated serotonin production or changes in melatonin production (Avery, 2020a). A mismatching between sleep patterns and circadian rhythms has also been hypothesized as an underlying cause (Avery, 2020a; Meester & Gordijn, 2016).


If you suspect that you or someone you care about may be experiencing SAD, do not hesitate to seek professional help. It is always better to be proactive rather than waiting for symptoms to seriously affect your ability to function on a daily basis. Following is a discussion of some of the treatment modalities you might expect your healthcare provider to prescribe or recommend:

  • Several studies have demonstrated light therapy as a highly effective treatment for depression related to seasonal changes (Meesters & Gordijn, 2016). This stands to reason, given the hypothesis that seasonal mood changes stem from changes in exposure to natural light. A standard recommendation, based on the findings of a handful of studies (Meesters & Gordijn, 2016) is exposure to a 10,000 lux therapy lamp for 30-45 minutes at a time. Avery (2020b) recommends treatment with an antidepressant alone or combination of an antidepressant and light therapy for fall/winter depression. The author recommends limiting exposure to sunlight to no more than 13 hours per day for those who suffer from spring/summer depression.

  • Regular exercise and good sleep habits are important factors in managing any mood disorder. Avery (2020b) suggests daily walks outside to combat seasonal depression, as even a cloudy day can provide an exposure to an estimated 1000 to 5000 lux. Avery (2020b) cites three studies that looked at the effects of aerobic exercise in mitigating symptoms of seasonal depression, and each indicated improvement in depressive symptoms among study subjects who engaged in aerobic exercise. Duration and frequency of aerobic exercise employed in the studies ranged from 45 minutes twice per week to 1 hour every day.

  • Sleep hygiene refers to behaviors surrounding preparation for sleep that help promote a normal sleep-wake cycle. The American Association of Sleep Medicine suggests sleep hygiene practices such as keeping a consistent schedule, setting a bedtime which allows for at least 7 hours of sleep, avoiding exposure to bright light in the evening, avoiding consuming alcohol before bedtime, and avoiding caffeine in the late afternoon or evening. (AASM, 2017).


AASM (February 9, 2017). Sleep education: Healthy sleep habits. Retrieved from

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders, 5th ed. Washington, DC.; American Psychiatric Publishing

Meesters, Ybe, & Gordijn, Marijke CM. (November 30, 2016). Seasonal affective disorder, winter type: current insights and treatment options. Psychology Research and Behavior Management, 9, 317-327.

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