Severe, drenching night sweats that soak through clothing and bedding should not be dismissed as mere hormonal changes or a warm bedroom – they can be an early warning sign of cancer, oncologists have warned.
While the vast majority of night sweats are harmless, persistent episodes that recur over weeks or months without a clear explanation warrant proper medical assessment, said Dr Jiri Kubes, medical director at the Proton Therapy Center in Prague.
How certain cancers trigger the body’s thermostat to malfunction
Blood cancers, particularly lymphoma, are among the malignancies most frequently linked to this symptom. Research shows that Hodgkin and non-Hodgkin lymphoma, leukaemia, and a range of other cancers including carcinoid tumours, bone cancer, liver cancer, prostate cancer, kidney cancer, germ cell tumours, mesothelioma, advanced medullary thyroid cancer and ovarian cancer can all produce night sweats as a presenting feature.
The mechanism lies in the body’s own inflammatory response. When malignant cells are present, the immune system releases signalling proteins known as cytokines. These cytokines can act directly on the hypothalamus – the brain’s internal thermostat – causing it to raise core body temperature. The body then responds by sweating profusely in an attempt to cool down, especially during sleep when natural temperature regulation is already less stable.
“With certain cancers, the body produces inflammatory chemicals that can affect temperature regulation,” Dr Kubes explained. “This can lead to episodes of significant sweating during the night, sometimes enough for people to wake up with soaked clothing or bedding.”
The immune response and hormonal balance can both be disrupted by malignant conditions, triggering excessive perspiration while patients sleep. In lymphoma, abnormal proteins or hormones produced by the cancer itself may also interfere with the body’s temperature control.
Non-Hodgkin lymphoma is the eighth most common cancer in the UK, accounting for around three per cent of all new cancer cases annually – approximately 13,700 diagnoses each year. Hodgkin lymphoma is less common, with around 2,200 new cases diagnosed annually, and is notable for being one of the most frequent cancers among teenagers and young adults. Overall, about one in two people in the UK will develop cancer during their lifetime.
Why people delay seeking help
Many individuals fail to recognise the potential significance of night sweats because they readily attribute them to everyday factors such as anxiety, hormonal fluctuations during menopause, inadequate sleep quality or simply a warm bedroom.
“People often try to explain it away for months before seeking medical advice,” Dr Kubes said. “It’s usually the persistence of the symptom that becomes concerning rather than a single isolated episode.”
The National Health Service advises that night sweats have numerous benign causes, including menopause, anxiety, infections such as tuberculosis, medications including certain antidepressants and steroids, hormonal imbalances such as an overactive thyroid or low blood sugar, sleep disorders, alcohol or drug use, and other conditions such as autoimmune disorders, gastroesophageal reflux disease and hyperhidrosis. Cancer is a less common explanation, but one that should not be overlooked.
When night sweats demand a GP appointment
The oncologist noted that night sweats become considerably more concerning when they present alongside other indicators. These warning signs include losing weight without explanation – often more than ten per cent of body weight – experiencing persistent tiredness, noticing painless swelling of lymph nodes in the neck, armpits or groin, suffering from recurring fevers, or experiencing intense, persistent itching.
The NHS advises seeing a GP if night sweats regularly wake you up, worry you, or are accompanied by other symptoms such as unexplained weight loss, fever, persistent cough, diarrhoea, enlarged lymph nodes or spleen, unusual bruising or persistent pain.
Dr Kubes stressed that occasional sweating during the night is exceedingly common and typically poses no cause for alarm, particularly during warmer months or stressful periods. “If someone is experiencing regular drenching night sweats, particularly if they are waking repeatedly or noticing other symptoms, it’s important to speak to a doctor,” he said.
He added that while investigations may ultimately reveal nothing serious, it remains prudent to examine persistent bodily changes. Early cancer symptoms frequently overlap with far more commonplace conditions, making awareness of ongoing changes particularly valuable.
It is also worth noting that night sweats can arise as a side effect of cancer treatments themselves, including chemotherapy, hormone therapy, steroids, opioids and radiotherapy.