My mother recently died at the age of 70 while she was sleeping. She had been diagnosed with the flu two days earlier. We chose not to have an autopsy , however,the death certificate lists the cause of death as heart attack . Can you have a heart attack while you are sleeping and not wake up? If so, do you think the person feels pain? It s very important to us that she died peacefully as she had been awake and up and moving only two hours before it was discovered she had died. Thank you.