SAD, seasonal depression: symptoms and treatments

Seasonal affective disorder (SAD), also commonly named as seasonal depression¹, is a condition that occurs repetitively at certain times of the year². Those affected experience major depressive episodes in late autumn and winter, which alternate with periods of well-being in spring and summer². In rarer cases, the symptoms of depression can appear in the summer, in a form referred to as “summer depression” ² . In rarer cases³, seasonal affective disorder is associated with bipolar disorder and in these cases it includes a mood episode (depressive or manic or hypomanic) with a seasonal pattern². This disorder was first identified and described in 1984 and affects around 3% of the overall population². It is important that sufferers do not underestimate symptoms and ask for help, in order to receive the appropriate treatment and manage the condition optimally.

Symptoms of seasonal depression²

The symptoms of seasonal depression are in large part similar to those of “conventional” depression³. The symptoms of winter depression include low mood every day, for most of the day, along with feelings of hopelessness, powerlessness, guilt or worthlessness³. These feelings can lead individuals to withdraw socially and significantly neglect their self-care². They might also become physically slower, or conversely, more agitated, and experience cognitive symptoms, such as difficulty with     concentration and making decisions².
In addition to common depressive symptoms, other less frequent symptoms can include oversleeping and/or overeating, fatigue, craving certain foods, especially carbohydrates².
Unlike winter depression, summer depression symptoms are more likely to be accompanied by insomnia, decreased appetite and weight loss². 
Seasonal depression is a clinical diagnosis² and should not be confused with winter sadness or the “winter blues” that some people experience⁴. Lack of motivation, tiredness and sleep disturbances can also appear with the winter blues, but “winter blues” is not a clinical diagnosis and the symptoms are milder with no significant impact on day-to-day living, work and social life⁴.

Diagnosis of seasonal affective disorder

Regarding the definition of seasonal affective disorder, SAD is a subtype of major depressive disorder and of bipolar disorder with seasonal patterns². Seasonality plays an important role in accurately diagnosing seasonal depression and differentiating it from other types of depressive disorders and bipolar disorders². Doctors need to understand when symptoms first appear, how long they last and when they end during the year, and whether they recur from year to year². A diagnosis is based on a clinical interview and specific tests administered by a healthcare professional⁵. A diagnosis of SAD requires the same diagnostic criteria as major depression or bipolar disorder, with a seasonal pattern². 

In the presence of major depression (MDD) with a seasonal pattern, the patient must meet the criteria for MDD and present a seasonal pattern². In the case of bipolar disorder (BP), the criteria for BP must be present with at least one episode of mood alteration (depressive, manic or hypomanic) with a seasonal pattern².

Effective treatment for seasonal depression

There are several treatment options available, and they can often be used together². The main treatment indicated for seasonal depression is pharmacological, using antidepressants, such as selective serotonin reuptake inhibitors (SSRIs)². This can be accompanied by 30 minutes a day of light therapy using a special lamp that emits 10,000 lux, preferably in the morning². Psychotherapy, especially cognitive behavioural therapy, can also help by changing the thoughts and behaviours that contribute to depression². People with seasonal depression are often found to be deficient in vitamin D². Therefore, supplementation may be suitable, but always under medical supervision⁶.

Coping strategies

Changing a few habits can also be beneficial². A healthy diet, similar to the Mediterranean diet, may be an appropriate option, according to preliminary research⁷. Ensuring adequate sleep and practicing regular physical activity, such as taking a brisk walk every day⁸, can mitigate symptoms². Getting some sunlight, perhaps during a short lunchtime walk, and adopting stress coping strategies can also help².

Conclusion

Lifestyle changes and appropriately timed therapy are great ways to help deal with seasonal depression². Therefore, if you think you might have symptoms of SAD, it is important to ask for medical help promptly^2,9. With the right treatment, the prognosis – the predicted outcome of an illness – is generally positive².

References:

1. Cleveland Clinic (nonprofit, USA), Seasonal Depression (Seasonal Affective Disorder), 04/10/2022
2. Munir S., Gunturu S., Abbas M., “Seasonal Affective Disorder”. [Updated 2024 Apr 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK568745/
3. Avery D., “Seasonal affective disorder: Epidemiology, clinical features, assessment, and diagnosis”, in: UpToDate, Roy-Byrne P. P. (Ed), Solomon D. (Ed), 17 June 2024,
4. National Health Service (NHS, UK), “Symptoms - Seasonal affective disorder (SAD)”, 20 May 2022
5. National Institute of Mental Health (Nimh – NIH, USA), “Seasonal Affective Disorder (SAD): More Than the Winter Blues”
6. Onyemaechi C., American Psychiatric Association, “What is depression?”, April 2024
7. Columbia University Irving Medical Center, “What’s the deal with vitamin D?”, 24 August 2022
8. Swainson J., Reeson M., Malik U., Stefanuk I., Cummins M., Sivapalan S., “Diet and depression: A systematic review of whole dietary interventions as treatment in patients with depression”. J Affect Disord. 2023 Apr 14;327:270-278. doi: 10.1016/j.jad.2023.01.094. Epub 2023 Feb 3. PMID: 36738997, https://www.sciencedirect.com/science/article/abs/pii/S016503272300112X?via%3Dihub
9. National Health Service (NHS, UK), “Exercise for depression”, 20 May 2022
10. National Health Service (NHS, UK), “Overview - Seasonal affective disorder (SAD)”, 20 May 2022