I have long-standing COPD, (Bronchiectasis and Athsma), mild anemia, moderately elevated blood pressure, and I had bypass surgery 6 years ago. I often suffer from pericarditis, but contary to what you might expect, I live a healthy lifestyle. This week, for the first time in about 3 years I suffered an attack of the rigors on two consecutive very cold nights, while dressing for bed. I have been under a lot of pressure due to my wife s hospitalization for surgery and have felt extremely exhausted. I am sure I don t have any infections. Can exhaustion be the sole cause? Are the attacks dangerous?