I woke up this morning to a heart rate of over 150. what would cause this?

see dr.: There are several things that can cause a rapid heart rate, ranging from anxiety to more serious cardiac heart rhythm abnormalities. You need to see a cardiologist (heart dr) for an evaluation. Best wishes.

arrhythmia: Would be a serious condition to rule out, but also dehydration, anemia, hyperthyroidism. Call your doctor to discuss when you should be seen.