Seasonal depression is commonly associated with the short, dark days of winter, but health experts are warning that hot weather and prolonged heatwaves can also trigger a lesser-known form of the condition during the summer months.
Medical professionals say Summer Seasonal Affective Disorder (SAD) is a recognised type of depression that follows a seasonal pattern and can significantly affect daily life. Although far less common than winter SAD, experts stress that it should be treated as a serious mental health condition.
According to a recent study, summer SAD affects around 0.57% of the global population, compared with about 5% for the winter form of the disorder. Rising temperatures, frequent heatwaves and tropical nights have been identified as factors that can contribute to symptoms in vulnerable individuals.
Unlike winter depression, which is often linked to reduced daylight and social isolation, summer SAD is associated with excessive heat, disrupted sleep and physical discomfort. Symptoms may include insomnia, loss of appetite, anxiety, agitation and persistent low mood. In severe cases, the condition can interfere with work, relationships and everyday activities.
Adam Borland, a clinical psychologist at the Cleveland Clinic, said people experiencing symptoms may benefit from maintaining a regular daily routine, limiting exposure to extreme heat and making sleep a priority. He added that anyone with severe or persistent symptoms should seek professional medical care.
The warning comes as mental health conditions continue to rise across the world. A recent analysis from the Global Burden of Disease Study, published in The Lancet, estimated that approximately 1.2 billion people, or around 15% of the global population, were living with a mental health condition in 2023.
The study found that the number of people affected by mental health disorders increased by 95% between 1990 and 2023. During the same period, mental disorders climbed from the 12th to the fifth leading cause of health loss worldwide.
Major depressive disorder and anxiety disorders recorded some of the sharpest increases. Cases of major depression rose by 131%, while anxiety disorders increased by 158%, making them the two most common mental health conditions globally.
Researchers behind the Global Burden of Disease Study said meeting the growing demand for mental health services should be regarded as a public health priority, particularly for vulnerable groups.
The situation is also a concern across Europe. The World Health Organization estimates that one in six people in the European region, around 140 million individuals, lives with a mental health condition. Despite the high number of cases, only one in three people suffering from depression receive the treatment they need.
Health experts have also highlighted the lasting impact of the COVID-19 pandemic. Depression and anxiety among young people have increased by an estimated 25% since the pandemic, while suicide has become the leading cause of death among people aged 15 to 29 in the European region.
