Understanding Seasonal Depression

Depression

Typically, during the winter, as days grow shorter and temperatures drop, many people notice changes in their mood and energy levels. This can commonly include feeling sluggish; however, for some people, the seasonal shift brings something deeper and more disruptive: seasonal depression, also known as Seasonal Affective Disorder  (SAD). This form of depression often occurs in late autumn and winter and improves as daylight/sunlight increases in spring.  

Some signs and symptoms of seasonal depression include: 

• Persistent low mood 

• Loss of interest in normal activities 

• Difficulties waking up / Increased need for sleep 

• Craving for carbohydrates 

• Fatigue, low motivation, or ‘mental fog’ 

• Social withdrawal 

Seasonal depression occurs due to a range of biological changes triggered by a decrease in sunlight during the winter months. With less daylight, the body’s internal clock/circadian rhythm becomes disrupted, affecting sleep, mood, and hormone regulation. Lower light exposure can also lead to a decrease in serotonin, the neurotransmitter linked to happiness and emotional stability, increasing vulnerability to low mood. At the same time, the body produces more melatonin in darker seasons,  which can cause increased tiredness and sluggishness. Furthermore, limited sunlight can result in lower vitamin D levels, a deficiency that has been consistently linked to changes in mood and overall well-being; together, these factors contribute to the onset of seasonal depression. 

Seasonal depression affects millions of people worldwide, with certain factors increasing the likelihood of developing the condition. It is most common in regions with low levels of sunlight; research shows that countries at higher latitudes, particularly in northern Europe (such as Greenland, Finland and Norway), report higher rates of SAD  due to shorter winter days (Kim et al, 2025). Other risk factors include a family history of depression or SAD and age, as SAD often first appears between 18 and 30 years.  Women are also more frequently diagnosed than men, reflecting potential biological,  hormonal, and social influences.  

Recognising these risk factors early in the season is essential to prevent symptoms from worsening and to implement effective management strategies that support a better quality of life. While professional diagnosis and treatment remain important, many individuals find relief through adjustments in daily habits and lifestyle. Spending time outdoors, even brief walks - particularly in the morning - can help regulate the body’s internal clock. Regular physical activity and exercise can also boost the production of mood-enhancing endorphins, aiding in the management of SAD.

Maintaining social connections, even though virtual interactions are beneficial, as isolation can exacerbate symptoms. Additionally, prioritising sleep by keeping consistent sleep/wake times, limiting screen exposure before bed, and consuming a balanced diet to provide nutritional support can further help reduce the impact of seasonal depression.  

In summary, seasonal depression is a common yet often overlooked condition that can significantly impact daily life during the darker months. Awareness of the risk factors,  early recognition of symptoms, and proactive lifestyle adjustments, alongside professional support when needed, can help individuals manage SAD effectively and maintain their well-being throughout the winter season.  

Reference: 

1. Kim, K., Kim, J., Jung, S., Kim, H.-W., Kim, H.-S., Son, E., Ko, D. S., Yoon, S., Kim,  B.S., Kim, W. K., Lim, C., Kim, K., Lee, D., & Kim, Y.H. (20205). Global prevalence of seasonal affective disorder by latitude: A systematic review and meta-analysis. Journal of Affective Disorders, 390, 119807.  

https://doi.org/10.1016/j.jad.2025.119807