Cancer: Symptoms may include excessive, reduced or absent sweating

It is usually caused by marked changes in hormone levels, which are perturbed by cancer itself or the treatment for the disease.

It is unclear why some types of cancer cause patients to sweat exclusively at night, but experts hypothesise it may be a side effect of the body fighting off the disease.

There is evidence, however, that when night sweats are caused by cancer, other symptoms are likely to occur.

When changes in sweating patterns are caused by Horner’s disease, patients may also notice the iris colour of the affected eye differs slightly from the unaffected eye; it is generally lighter.