Dear, I have gone through your question and I can understand your concern. Melatonin is a manmade form of a hormone produced in the brain that helps regulate your sleep and wake cycle and has been used in alternative medicine as a likely effective aid in treating insomnia (trouble falling asleep or staying asleep). The most common melatonin side effects include: daytime sleepiness, headaches, dizziness. Other, less common melatonin side effects might include abdominal discomfort, mild anxiety, irritability, confusion and short-lasting feelings of depression. There s no data about bad dreams, but that may be from melatonin. Melatonin doesn t cause hypertension, it s also possibly effective in treating high blood pressure. Your nosebleeds is due to hypertension, so get a general check up for it. Please don t forget to give your valuable feedback and five star rating, to help me assist you in a better way. Click at I Find This Answer Helpful too . Please, write a review about your experience with me.