Dear Doctor,Recently I had undergone subdural haematoma surgery on my left brain.I am a 68 ears man,my other medical parameters like sugar is normal,hemoglobin no.11,blood preasure is 80/130.I have been suffering from sudden cold & body sweating.It hold for few minutes & normally occurred at sleeping position.Now taking medicine to improve hemoglobin level.Kindly explain me what is the causes of above problem.It breaks my sleeping time.I hardly sleep for 4 hours.Kindly help.With thanks,Nandan Ghosh INDIA