If you've been waking up drenched in sweat at night, it could be more than just a hot bedroom. TikTok doctor Dr James Williams, who has more than 200,000 followers on the platform, warns that people over the age of 40 who frequently experience night sweats could be suffering from a serious and contagious infection - or worse.

One condition linked to this uncomfortable symptom is tuberculosis (TB), a bacterial infection that mainly affects the lungs. The World Health Organization (WHO) explains TB spreads through the air whenever someone with the illness coughs, sneezes or breathes, making it easily spread in close quarters.

Globally, WHOreports that 10.7 million people fell ill with TB in 2024 with around 1.23 million deaths. It remains one of the world's deadliest infectious diseases.

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Common symptoms include prolonged cough, chest pain, fever, fatigue and night sweats. WHO warns these symptoms typically develop slowly, which increases the risk of spread before diagnosis.

The organisation warns that a person with untreated TB can infect 10 to 15 other people in a year, highlighting why early detection is crucial. It is airborne, and even a few inhaled bacteria can lead to illness.

Treatment usually involves a six-month course of antibiotics such as rifampicin and isoniazid. Completing the full course is important to preventing drug-resistant TB, which is far harder to treat.

While TB is a known cause of night sweats, it could have various other possible causes. NHS guidance notes how they can also be linked to menopause, certain medications, infections like HIV, endocrine disorders, and even some cancers.

The Mayo Clinic adds that night sweats may accompany conditions including endocarditis, autoimmune disorders, and other infections. Persistent or unexplained night sweats should always be evaluated by a clinician to rule out serious causes.

Because the symptom could indicate anything from a minor hormonal change to a serious, contagious disease, health professionals advise anyone over 40 experiencing frequent night sweats to seek medical advice promptly. Early investigation can help catch conditions like TB before they become severe.

Viewers of Dr Williams' TikTok video shared their own experiences in the comments with one saying: "I have them, late 50s and I've gone through menopause and hyperthyroidism." While another added: "I have it as a result of sarcoidosis."

"I have been experiencing it, I consulted a doctor last week and it was hyperthyroidism and I am on medication now," admitted a third. Another commented: "I was 28 when I had severe night sweats, I had 4B Hodgkin lymphoma."