Heart rate bracelet is a very low radiation electronic products, long-term wear heart rate bracelet to sleep is not particularly harmful. Because the heart rate bracelet can monitor the human heart rate, when waking up, if found in the process of sleep heart rate is too fast or too slow, and in the process of sleep and no obvious feeling, should be based on the abnormal heart rate timely medical care. The normal human heart rate range is 60-100 beats/min, if lower than 60 beats/min belongs to bradycardia, higher than 100 beats/min belongs to tachycardia. Heart rate bracelet can monitor the time of arrhythmia, if at this point there is a clear discomfort, you should immediately seek medical attention and do ECG or 24h ambulatory ECG to monitor whether there is a specific arrhythmia, and the nature of the arrhythmia.