Seasonal affective disorder (SAD) was first described as a syndrome in 1984 by Rosenthal, et al.1 An estimated 10% to 20% of recurrent depression cases follow a seasonal pattern.2 It appears to be most common in young adults and women, with the reported gender difference ranging from 2:1 to 9:1.3 In addition, there are cultural and ethnic differences in sensitivity to SAD. One study found that African individuals living in the Washington, DC, area had higher rates of SAD compared with other populations.4 Another study found higher rates of differences in SAD between men and women in Italy compared to gender differences in India.5
Criteria laid out in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5)6 specify that depression with a seasonal pattern must include having depression that begins and ends during a specific season every year (with full remittance during other seasons) for at least two years, and having more seasons with than without depression over a lifetime. Although winter is the season most commonly associated with SAD, some people experience SAD during the summer.
SAD often goes unreported and is therefore underdiagnosed,7,8 even when it occurs in the more typical winter pattern. Because summer SAD is less common, it is even less likely to be diagnosed.
“We know much less about ‘summer SAD’ or ‘reverse SAD,’ as it is sometimes called, than we know about winter SAD, and there isn’t much literature about it,” Kelly Rohan, PhD, Professor and Director of Clinical Training, Department of Psychological Science, University of Vermont, Burlington, told Psychiatry Advisor.
“Overwhelmingly, the most common presentation of SAD is winter pattern, but there are people who experience depression in the summertime and feel at the[ir] absolute best in the winter,” she said.
Is It Really SAD?
To determine whether depression occurring during the summer is actually SAD, psychosocial stressors that might account for the depression must be ruled out, Dr Rohan noted.
“None of the following scenarios are summer SAD,” she said.
“Someone who is unemployed every summer season might feel depressed and even meet criteria for clinical depression because suddenly they have unstructured time or miss their employment setting, but this isn’t SAD,” she said.
Parents who have the stress of keeping young children occupied all day because they are off from school or college students who are home for the summer and miss their routines or autonomy may become depressed. Some parents may feel stress because they are paying for expensive vacations, summer camps, or babysitters for their children. All of these affective symptoms are circumstantially triggered.
Many people “may feel embarrassed how they look in shorts or bathing suits, which can trigger depression, but that likewise isn’t SAD—it’s an underlying body image problem,” Dr. Rohan pointed out.
Finally, mood may be affected during the summer by “anniversary reactions” in which some traumatic event — a death, a divorce — might have taken place during a previous summer and may evoke loss reactions.
Individuals with SAD seem to have higher sensory processing sensitivity, which makes them more vulnerable to environmental factors,9 some of which take place in the summertime, Dr Rohan said.
Heat and humidity may play a role in increasing the risk for summer SAD. A study comparing individuals with SAD in Italy vs India found that there was a higher predominance of winter SAD in Italy and summer SAD in India, possibly due to the higher summer temperatures in India compared with Italy.5 Another study performed in Australia found a 9-fold higher incidence of summer SAD vs winter SAD in a tropical climate with heat and humidity described as the two most influential factors affecting mood and behavior.10 The researchers noted that the “summer-winter ratio is typically reversed in more temperate latitudes.”
“Most people with summer depression say that they feel better when they travel north during the summertime,” Dr Rohan observed.
“For example, people primarily [living] in the Washington, DC area, sometimes have reported improvement in mood when they traveled to New England during the summer, which is opposite to those with winter SAD, who say that they travel to the south in the winter and feel better,” she continued.
She noted that key neurotransmitters of mood regulation — norepinephrine, dopamine, and serotonin — also play a role in thermoregulation.11 Individuals who have an underlying vulnerability to mood disorders often also have issues with thermoregulation, which could be triggered by the heat and humidity.12
For some people, the increased length of the day, or — seemingly paradoxically — an excess of light, can be associated with summer SAD, according to Dr Rohan. One study, for example, found a correlation between suicide rates and longer duration of sunshine.13
Some research points to allergies as the culprits in summer SAD, Dr Rohan noted. Several studies have found that pollen is associated with an increase in depression14,15 and summer SAD typically starts in late spring when pollen counts are rising. One study found that rising pollen counts were associated with summer SAD, but not with winter SAD.16
“There is a cognitive component of summer SAD,” Dr Rohan noted. “People with summer SAD sometimes think, ‘Everyone else is happy and enjoying the summertime, so what’s wrong with me?’ In the winter, there is a parallel line of thought: ‘Everyone is happy during the holidays, so what’s wrong with me?’”
These thoughts “lead to further negative thinking and rumination, dwelling on how awful summer is, and how much the person hates summer, which in turn, increases the depression,” she said.
Summer Vs Winter Presentations
Symptoms of both summer and winter SAD are the same as the symptoms of depression, but with a seasonal component.
“We are looking for the presence of at least 5 out of 9 symptoms lasting most of the day nearly every day for 2 weeks, causing distress, and significant impairment in domains such as employment, relationships, and tending to responsibilities,” Dr Rohan said.
However, the particular presenting symptoms differ somewhat between winter and summer SAD (Table 1). “These symptoms, if they occur seasonally, are important clues in the type of SAD the patient has,” she added.
The Seasonal Pattern Assessment Questionnaire (SPAQ), a retrospective, self-administered tool, can be a useful diagnostic tool. It has been demonstrated to have high reliability, although low specificity, which may misclassify individuals without non-seasonal depression.8 Nevertheless, it is a helpful starting point. The questionnaire is available to the public and no training is required to use it.
Treatments to Ameliorate Summer SAD
Dr Rohan recommended several interventions to ameliorate the symptoms of summer SAD depending on an individual’s particular trigger.
For people whose symptoms are associated with heat and humidity, thermal interventions such as remaining in air conditioned and less humid settings might be helpful.
Dr Rohan noted that Wehr and colleagues reported a case in which a woman with bipolar disorder whose symptoms were triggered during summer heat agreed to be confined to an air conditioned house and take cold showers 5 times daily. Her symptoms improved to normal range but she relapsed 9 days after returning to normal summer conditions.17
For individuals whose symptoms might be triggered by longer light duration, “I could see a case for room-darkening shades or light-blocking curtains to simulate winter,” Dr Rohan suggested.
Addressing allergens might be a helpful approach for people whose symptoms are allergically triggered, Dr Rohan suggested.
Cognitive behavioral therapy (CBT) has been shown to be effective in improving symptoms in winter SAD8 and should also be useful for summer SAD. “Therapy targeting the rumination, negative thinking, and tendency to socially isolate during the summer can be as helpful as it is during the winter,” she stated.
CBT may be helpful in preventing relapse.8 “My research has found that CBT is an effective, durable treatment, perhaps because people learn skills in treatment — to think and behave differently and respond to seasonal changes differently — so they have a plan to prevent future relapse.” Dr Rohan added.
Success in the implementation of SAD prevention, however, “does not solely depend on the willingness of the patients, but is also influenced by external factors. Raising awareness of SAD among general practitioners and low-level access to mental-health support could help patients find appropriate help sooner,” according to a 2018 study of preventive approaches.18
A Growing Problem
Summer SAD may increase in the coming decades, as global warming may bring higher temperatures and possibly more humidity and air-borne allergies, Dr Rohan commented. She added, “Summer SAD is a wide-open area for research, which will likely be even more necessary if the condition becomes more widespread.”
- Rosenthal NE, Sack DA, Gillin JC, et al. Seasonal affective disorder—description of the syndrome and preliminary findings with light therapy. Arch Gen Psychiatry. 1984;41(1):72-80.
- Roecklein KA, Rohan KJ. Seasonal affective disorder: an overview and update. Psychiatry (Edgmont). 2005;2(1):20-26.
- Magnusson A. An overview of epidemiological studies on seasonal affective disorder. Acta Psychiatr Scand. 2000;101:176-184.
- Guzman A, Rohan KJ, Yousufi SM, et al. Mood sensitivity to seasonal changes in African college students living in the greater Washington D.C. metropolitan area. ScientificWorldJournal. 2007;7:584-591.
- Tonetti L, Sahu S, Natale V. Cross-national survey of winter and summer patterns of mood seasonality: a comparison between Italy and India. Compr Psychiatry. 2012;53(6):837-842.
- American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Arlington, VA: American Psychiatric Association; 2013.
- Lurie SJ, Gawinski B, Pierce D, Rousseau SJ. Seasonal affective disorder. Am Fam Physician. 2006;74(9):1521-1524.
- Melrose S. Seasonal affective disorder: an overview of assessment and treatment approaches. Depress Res Treat. 2015;2015:178564.
- Hjordt LV, Stenbæk DS. Sensory processing sensitivity and its association with seasonal affective disorder. Psychiatry Res. 2019;272:359-364.
- Morrissey SA, Raggatt PT, James B, Rogers J. Seasonal affective disorder: some epidemiological findings from a tropical climate. Aust N Z J Psychiatry. 1996;30(5):579-586.
- Chauhan NR, Kapoor M, Prabha Singh L, et al. Heat stress-induced neuroinflammation and aberration in monoamine levels in hypothalamus are associated with temperature dysregulation. Neuroscience. 2017;358:79-92.
- Lõhmus M. Possible biological mechanisms linking mental health and heat—a contemplative review. Int J Environ Res Public Health. 2018;15(7):1515.
- Vyssoki B, Kapusta ND, Praschak-Rieder N, Dorffner G, Willeit M. Direct effect of sunshine on suicide. JAMA Psychiatry. 2014;71(11):1231-1237.
- Postolache TT, Lapidus M, Sander ER, et al. Changes in allergy symptoms and depression scores are positively correlated in patients with recurrent mood disorders exposed to seasonal peaks in aeroallergens. ScientificWorldJournal. 2007;7:1968-1977.
- Manalai P, Hamilton RG, Langenberg P, et al. Pollen-specific immunoglobulin E positivity is associated with worsening of depression scores in bipolar disorder patients during high pollen season. Bipolar Disord. 2012;14(1):90-98.
- Guzman A, Tonelli LH, Roberts D, et al. Mood-worsening with high-pollen-counts and seasonality: a preliminary report. J Affect Disord. 2007;101(1-3):269-274.
- Wehr T A, Sack D A, Rosenthal N E. Seasonal affective disorder with summer depression and winter hypomania. AJP. 1987;144(12):1602-1603.
- Nussbaumer-Streit B, Pjrek E, Kien C, et al. Implementing prevention of seasonal affective disorder from patients’ and physicians’ perspectives – a qualitative study. BMC Psychiatry. 2018;18(1):372.
Table 1. Symptoms of Winter and Summer SAD8
Winter SAD Summer SAD – Increased appetite
– Carbohydrate cravings
– Weight gain
– Psychomotor retardation
– Social withdrawal
– Loss of interest in activities
– Decreased appetite
– Weight loss
– Psychomotor agitation
– Social withdrawal
– Occasional violent behavior