Regarding suspension of government duty

I am an engineer in jammu and kashmir state electricity department. My office head is asking me to move to a job position where i am required to give night shifts. I am suffering from a digestive system problem since the last six years due to which i have to often take sleep medication as this problem also interferes with my ability to sleep at night. I explained this to my office head but he threatened me with suspension for dereliction of duty. Kindly help.