Writer: Lois Ng
Editor: Lorrine Sum
Artist: Ahmad Bilal
Seasonal Affective Disorder (SAD) is sometimes known as “winter depression” as symptoms become increasingly apparent during the winter months. Although less documented, some individuals may have SAD symptoms during the summer instead.
Symptoms and Diagnosis
SAD is characterised by a recurring pattern of depressive episodes that coincide with specific seasons. Common symptoms include:
- Persistent low mood
- Loss of interest in activities
- Low energy and fatigue
- Sleep disturbances, e.g. oversleeping
- Changes in appetite, e.g. craving carbohydrates
- Difficulty in concentration
To diagnose SAD, clinicians often use the DSM-5, which requires at least 2 consecutive years of seasonal depressive episodes without non-seasonal episodes (NHS).
The History of SAD
The term ‘Seasonal Affective Disorder’ was first coined in the early 1980s by Dr. Norman E. Rosenthal, a psychiatrist and researcher at the National Institute of Mental Health (NIMH). Dr. Rosenthal and his team were investigating the link between seasonal changes and mood disturbances, inspired in part by his own experiences of mood shifts after moving from South Africa to the United States.
In 1984, Rosenthal published a landmark study in the journal Archives of General Psychiatry, which formally described SAD as a distinct clinical condition. His team explored these observations in 12 individuals who exhibited recurring depressive episodes during the summer months. In a subsequent paper, he analysed a group of 60 participants, evenly split between those with summer SAD and winter SAD. While both groups satisfied the criteria for clinical depression, they displayed distinct symptom profiles. The winter group described themselves as “very lethargic”, like hibernating animals. The summer half, however, reported irritability, restlessness, insomnia and reduced appetite (Rosenthal et al, 1987).
This research not only brought widespread attention to the phenomenon but also highlighted the potential effectiveness of light therapy as a treatment. Rosenthal’s work laid the foundation for subsequent research and the inclusion of SAD in the Diagnostic and Statistical Manual of Mental Disorders (DSM).
The Science behind SAD
While the cause of SAD is linked to seasonal changes, the precise etiology of SAD is not fully understood. Nevertheless, researchers believe the disorder stems from both biological and environmental factors.
The circadian rhythm, often referred to as the body’s internal clock, regulates sleep-wake cycles, hormone release, and other essential bodily functions. During the fall and winter months, shorter days and reduced sunlight can desynchronize this internal clock, leading to disrupted sleep patterns and mood regulation. Research using light therapy has demonstrated that re-aligning the circadian rhythm can alleviate SAD symptoms.
Serotonin is a neurotransmitter critical for maintaining mood balance. Exposure to sunlight is known to increase serotonin levels through pathways involving the retina and brain. Reduced sunlight in winter can lead to lower serotonin activity, contributing to depressive symptoms. This connection is supported by studies showing that individuals with SAD often exhibit lower serotonin transporter binding in their brains during winter months (Praschak-Rieder et al, 2008; Tyrer et al, 2016).
Melatonin, a hormone produced by the pineal gland, plays a vital role in regulating sleep. Its production is influenced by light exposure, with darkness triggering its release. During winter, prolonged darkness can lead to elevated melatonin levels, causing increased lethargy and difficulty waking up in the morning. Overproduction of melatonin is thought to amplify the fatigue commonly experienced in SAD.
There is evidence that individuals with SAD may have genetic predispositions affecting serotonin and dopamine pathways, making them more sensitive to seasonal changes. Variants in genes such as SLC6A4, which is involved in serotonin transport, have been studied in relation to SAD susceptibility (Tyrer et al, 2016; Norgaard et al, 2017). Neuroimaging studies also suggest differences in the brain structure and function of those with SAD, particularly in areas like the hypothalamus and prefrontal cortex (Borchardt et al, 2015). A family history of depression or other mood disorders can further increase susceptibility (Stamenkovic et al, 2001).
In addition to biological mechanisms, environmental factors like geographic location and lifestyle changes play a significant role. People living farther from the equator experience more pronounced seasonal light variations, increasing their risk. Social isolation and reduced physical activity during colder months can further compound the condition.
Treatment and interventions
Light therapy
The National Institute for Health and Care Excellence (NICE) recommends managing SAD similarly to other types of depression, including treatment options like talking therapy, cognitive behavioural therapy (CBT) or medication. However, increasing evidence has shown that light therapy can be effective in relieving symptoms. This involves exposure to bright light for around 30 minutes in the early mornings, typically through a special lamp called a light box that simulates natural sunlight. This can help reset the circadian clock, reducing melatonin production and boosting serotonin production. Several studies have supported phototherapy in alleviating depressive symptoms and can be considered as a clinical therapy of treatment for SAD (Pjerk et al, 2020; Tao et al, 2020; Chen et al, 2024).
Talking therapies
Cognitive behavioural therapy specifically tailored for SAD (CBT-SAD) helps individuals develop coping strategies to manage negative thought patterns and behaviours. Research has demonstrated that CBT-SAD can provide long-lasting benefits, even beyond the seasonal episodes (Meyerhoff et al, 2018; Rohan et al, 2004).
Medication
Antidepressants, such as selective serotonin reuptake inhibitors (SSRIs) often used to treat depression, are also sometimes prescribed to treat more severe cases of SAD, addressing the chemical imbalances associated with SAD. Clinical trials have shown that SSRIs can be particularly effective when combined with light therapy (Lam et al, 2016; Rohan et al, 2004).
Lifestyle Changes
Simple adjustments in everyday life can also make a difference. Regular exercise, a balanced diet and maximising exposure to sunlight during the day, such as sitting near windows when indoors, can all contribute to improved mental health during these winter months (NHS).
“Winter is coming”
While winter’s arrival might seem daunting to individuals prone to SAD, early recognition and intervention can prevent the disorder from overshadowing the season. And hey, maybe turning into a human burrito is just what the doctor ordered. By fostering open conversations and destigmatising mental health struggles, we can ensure that no one has to face these winter months alone.
kinesismagazine.com 