Dear I can understand your concern . You have only increased heart rate no other problems .first we need to know that whether it is present whole day and night or its is present only for some time of day or with some situations . Is there any aggrevating or relieving factors.is there any other complaints also especially shortness of breath, chest pain or dizziness . Increase in the heart rate has many causes such as anaemia ,hyperthyroidism , anxiety , fever, any cardiac illness ,any infection , drugs etc.to know the exact cause of your problem we need complete history and examination .If needed we can run some blood test and do an ecg etc..so I would like to suggest you that don t be sad a or anxious about that..consult to our physician for this. He will evaluate you properly and treat you accordingly .