Dr. Hanif warmly Welcomes you! Thanks for consulting me at virtual clinic. I have carefully worked through your case, and I can realize your health worries. Being your physician, I assure you not to worry as I will take care all of your medical concerns.   Yes melatonin has a very mild effect on increasing heart beat. But its not a major side effect of the drug. Make sure if:- your timing and dosage of taking the drug is correct? You don t have a comorbid disease e.g anxiety, hyperthyroidism, high blood pressure? Your physician will assist you to rule them all out. If you need further, detailed and quick assistance related to any health issues, feel free to ask me a question directly from my profile. You can also attach Lab reports and pictures with direct question. Have a wonderful time ahead. Please don t forget to give your valuable feedback and five star rating, to help me assist you always in a better way. Click at Thanks & I Find This Answer Helpful too. Please, write a review on my profile, about your experience with me.   Regards! DR. MUHAMMAD M. HANIF PHILADELPHIA, USA