A raise in heart rate without accompnying extercise can be caused by various things - anxiety, stress and illness among them. Ive got a fitbit on the tracks my HR - over the last week Ive had a rotton chest infection and my HR has gone up significantly. My normal resting HR is around 63 - its been higher this week at up to 76. similarly it normally dips into mid 50s overnight, but last night was the first time its gone there for a week which seems to tie in with fact that my temperature has finally gone back to normal.
Scared the bejesus out of me when it shot up so I consulted the fitbit forum and found that others have found HR goes up with infection.
Im also 60+ T2