Betaloc, also known as metoprolol tartrate, is not recommended to be taken at night due to the high risk and possibility of adverse effects. Metoprolol tartrate is used in the treatment of hypertensive angina pectoris, myocardial infarction, arrhythmias, hyperthyroidism, and variant angina pectoris. Contraindications include cardiogenic shock, symptomatic bradycardia, unstable angina, and bronchial asthma. Adverse reactions include dizziness, headache, bradycardia, nausea and vomiting. Treatment of myocardial ischemia, the heart’s ejection function decreases at night compared to the daytime, after taking the drug, the heart’s ejection will further decrease, once the ejection of blood can not meet the body’s needs, there may be a risk of sudden death and so on, it is recommended to take it in the morning or afternoon. Treatment of hypertension, the human blood pressure has two peak periods, respectively, in the morning 6:00-10:00, 4:00-8:00 p.m., the night blood pressure is lower, if you take it at night, it may lead to excessive drop in blood pressure and danger, it is recommended that you take it in the morning or at noon. To treat tachycardia, choose to take the drug when the heart is more excited, such as in the morning or afternoon, the heart rate will be slower in the evening than during the day, and life-threatening cardiac arrest may occur when taking drugs to control the heart rate. Take your medication as prescribed by your doctor.