By Mikey Smith MORE than a third of NHS employees have had to take time off work with mental health issues in the past year, a new survey has found. UNISON, the union which carried out the survey of 12,000 health workers across the UK, said the findings reveal burnout among employees and mean many more could quit the profession altogether. Nurses, porters, 999 call handlers and other NHS staff reported panic attacks, high blood pressure, chest pain and headaches \- with some also experiencing depression, sleepless nights and flashbacks. Helga Pile, UNISON head of health said: “Many NHS staff a…