Health professionals have raised concerns that prolonged loneliness and social isolation may significantly increase the risk of cardiovascular diseases, depression, sleep disorders, and other serious health conditions.

According to public health experts, feelings of loneliness can cause the body to produce an excess of stress hormones, such as cortisol. This hormonal imbalance can lead to elevated blood pressure, heart rate, and blood sugar—factors that are known contributors to heart disease and diabetes.

On Monday, the World Health Organization (WHO) revealed that loneliness claims the lives of at least 871,000 people globally each year. The organization further stated that one in six individuals around the world suffers from loneliness, which can manifest in both mental and physical illnesses.

Medical research indicates that loneliness increases the likelihood of heart attacks, strokes, diabetes, depression, anxiety, and suicidal behavior. The WHO also found that socially isolated teenagers are 22% more likely to underperform academically, while lonely adults often face difficulties maintaining employment.

In an exclusive interview with PUNCH Healthwise, health experts stressed that loneliness can weaken the immune system and diminish the body’s ability to fight infections, increasing vulnerability to illnesses including cancer.

Professor Tanimola Akande, a public health specialist from the University of Ilorin, explained that loneliness can exacerbate mental illness, diabetes, and heart conditions. He noted that socially isolated individuals are often inactive, which may lead to obesity, high blood pressure, and related complications due to unburned calories.

“Being alone for extended periods limits physical activity and social engagement,” he said. “This contributes to a sedentary lifestyle and makes individuals more prone to diseases like heart attacks, strokes, diabetes, depression, anxiety, substance abuse, suicidal thoughts, and even dementia.”

He added that lonely individuals are often trapped in cycles of negative thinking, and in some cases, loneliness itself may stem from underlying conditions such as depression.

Supporting this view, Dr. Timothy Olusegun, another public health physician, explained that loneliness elevates cortisol levels in the body, which in turn fuels inflammation and chronic illness. He highlighted that social isolation can raise mortality risk by as much as 30%.

“This is a critical health issue,” Dr. Olusegun stated. “Loneliness affects virtually every aspect of well-being. Isolated individuals often have poor dietary habits, lack exercise, and experience disrupted sleep patterns—all of which further harm their health.”

He added that adults experiencing chronic loneliness have a 40% higher chance of developing cognitive disorders, including dementia.

Dr. Olusegun also warned of the risk of chronic inflammation in lonely individuals, which can lead to serious diseases such as type 2 diabetes, heart disease, rheumatoid arthritis, and cancer.

“While inflammation is a normal immune response to injury or infection,” he said, “chronic inflammation happens when the body continues to send out distress signals without a clear cause, paving the way for long-term health issues.”

The WHO’s findings also reveal that one in three elderly individuals and one in four adolescents experience social isolation. The organization emphasized the urgent need to create physical spaces that encourage face-to-face social interaction without the interference of digital devices.

A separate study published in the Proceedings of the National Academy of Sciences also found a biological link between loneliness and poor health. Led by Professor John T. Cacioppo of the University of Chicago, researchers observed that lonely adults showed increased activity of CTRA genes in white blood cells—genes associated with inflammation and reduced immunity.

The study, involving 141 adults aged 50 to 68, revealed that loneliness not only increased harmful gene expression but also predicted future feelings of isolation and vice versa—creating a feedback loop of declining health and deepening loneliness.

The researchers conducted similar tests on rhesus macaque monkeys, a highly social species, housed at the California National Primate Research Centre. Results showed that socially isolated monkeys also exhibited elevated CTRA gene expression and increased norepinephrine levels, a stress hormone associated with the body’s fight-or-flight response.