Hello! Thank you for your question! I understand your concern. Short answer : You should take him to a medical physician to have a physical examination and a routine blood test. Detailed answer : Insomnia is a common problem in old patients. Loss of smell and night sweating is more concerning . I think that these problems could be caused by a neuorological problem , like a brain tumor in the frontal cortex or an infection . The gradual progression of the symptoms lead more to these causes. Dementia ( spontaneous due to the age or after repeated brain stroke ) could also be the cause of these symptoms . It can lead to loss of smell and insomnia in the first stages. A routine blood test should be done to exclude inflammation from an infection etc, which could lead to night sweating. A physical examination should be done to exclude neurological signs. Also a head CT scan or MRI would be very helpful. I would like to know if you have noticed memory problems lately . A detailed cognitive test by a neurologist is needed to determine this. Wish to have been helpful to you . Thank you for using HCM! Abaz Quka, neurologist