I have a friend who is experiencing night sweating due to a medical condition. Is there any known cause? It’s been going on for about 4 years now and doctors can’t find anything wrong with him. He has no history of skin cancer or other skin disorders, but he does sweat alot at night when his body temperature should be dropping. I’ve told him that it may not be the best idea to wear his long sleeved flannel shirts in bed while sleeping because they tend to make him even more warm during the night….but he says that doesn’t help much. What could this possibly be?