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.

Scientists at the University of Oxford have launched the world’s first human clinical trial of a vaccine targeting the Bundibugyo strain of Ebola as health authorities work to contain a growing outbreak in the Democratic Republic of the Congo and Uganda.

The Phase I trial will evaluate the vaccine’s safety and its ability to trigger an immune response in 50 healthy adult volunteers aged between 18 and 55. Researchers have begun recruiting participants, with vaccinations expected to start in the coming weeks after regulatory approval for the study.

The trial comes as the Bundibugyo Ebola outbreak continues to expand across Central Africa. According to the Democratic Republic of the Congo’s Ministry of Health, 1,926 confirmed cases and 702 deaths had been recorded across five provinces as of July 11. Uganda reported 20 confirmed infections, including two deaths, on July 12. Health officials have identified 10 provinces in Congo, including the capital Kinshasa, as high-risk areas.

The University of Oxford’s Vaccine Group said the study represents the first effort to test a vaccine specifically designed to protect against the Bundibugyo strain in humans. While vaccines exist for other Ebola virus species, no approved vaccine currently targets Bundibugyo Ebolavirus.

Nicole Lurie, Executive Director of Preparedness and Response at the Coalition for Epidemic Preparedness Innovations (CEPI), described the trial as an important step in the international response to the outbreak.

“Every step that brings a safe and effective vaccine closer helps strengthen our ability to protect vulnerable communities, save lives and bring this outbreak under control,” Lurie said, adding that Oxford’s work marks a significant milestone in efforts to combat the disease.

Researchers are also preparing additional clinical studies in Uganda, subject to approval from local regulators. Those trials are expected to be carried out through a partnership involving the Medical Research Council/Uganda Virus Research Institute and the London School of Hygiene and Tropical Medicine’s Uganda Research Unit.

Jean Kaseya, Director General of the Africa Centres for Disease Control and Prevention, welcomed the progress while stressing the importance of maintaining rigorous scientific and regulatory standards.

He said that although early-stage clinical trials will not provide an immediate solution for communities currently affected by the outbreak, they remain essential for developing medical tools capable of responding to both the current emergency and future Ebola outbreaks.

The Bundibugyo strain is one of several Ebola virus species known to infect humans and has caused multiple outbreaks in Africa over the past two decades. Public health officials continue to focus on surveillance, patient care, contact tracing and infection control measures while researchers work to develop vaccines and treatments that can help reduce the impact of the disease.

The Oxford trial is expected to provide initial data on the vaccine’s safety and immune response, laying the foundation for larger studies if the early results prove successful.

European law enforcement agencies have dismantled two international criminal networks involved in the production and distribution of counterfeit tobacco products, seizing 20 million illegal cigarettes and 38.4 tonnes of tobacco during a coordinated operation centered in Spain.

The operation, announced by the European Union’s Anti-Fraud Office (OLAF), targeted an illicit supply chain believed to be worth around €10 million. Investigators say the groups were involved in manufacturing, transporting and distributing counterfeit cigarettes across several European countries.

The crackdown was carried out through close cooperation between law enforcement agencies from Spain, Poland, Portugal and Lithuania, with support from OLAF and Europol.

During the operation last month, officers conducted 23 coordinated searches at residential properties, commercial buildings and industrial warehouses across the Spanish provinces of Alicante, Cuenca, Huelva, Murcia, Sevilla and Toledo.

Authorities recovered 20 million counterfeit cigarettes along with 38.4 tonnes of tobacco leaf and processed tobacco intended for illegal cigarette production. Investigators also seized tobacco manufacturing machinery, 18 vehicles, encrypted electronic devices, €170,000 in cash and several firearms believed to be connected to the criminal organizations.

A total of 50 suspects were arrested during the raids. Two of those arrested have since been transferred to Polish authorities as part of the cross-border investigation.

Officials believe the dismantled networks played a major role in supplying counterfeit tobacco products to illegal markets across Europe, depriving governments of tax revenue while strengthening organized crime groups involved in illicit trade.

OLAF Director-General Petr Klement said counterfeit tobacco products present both financial and public health risks.

“Smoking is dangerous,” Klement said. “Smoking counterfeit cigarettes is even worse.”

He added that the illegal trade not only exposes consumers to unregulated products but also diverts significant tax revenues away from public services while providing income for organized criminal networks.

The investigation reflects growing cooperation among European authorities to combat cross-border financial crime and illicit manufacturing. Counterfeit tobacco remains one of the most profitable illegal markets in Europe because of high consumer demand and substantial differences in tobacco taxation between countries.

Europol and participating agencies have increased intelligence sharing and joint operations in recent years to identify production facilities, disrupt supply routes and prosecute those responsible for illegal tobacco trafficking.

Officials said the investigation remains active and further arrests or seizures have not been ruled out as investigators continue examining evidence collected during the searches.

Authorities have urged the public to remain cautious when purchasing tobacco products from unofficial sources, warning that counterfeit cigarettes may contain harmful substances that do not meet safety standards and often finance wider criminal activities, including money laundering, illegal arms trafficking and other forms of organized crime.

The latest operation is being viewed as one of the largest coordinated actions against counterfeit tobacco networks in Europe this year, highlighting the scale of the illicit trade and the continued efforts by international authorities to dismantle criminal organizations operating across national borders.