Embodiments provide a wearable device and a method for monitoring a person wearing the wearable device. The wearable device includes sensors configured to generate signal of the person, data transmission component, data analysis device, monitoring device, and positioning components. The data transmission component receives and transmits the signal to the data analysis device. The data analysis device generates a pattern of the person based on the signal, then compares the pattern with one or more predetermined normal patterns of the person. When determining that the person is functioning abnormally, the data analysis device generates and transmits the alert instruction to a monitoring device to generate a notification for notifying a care-giver that the person is functioning abnormally. The positioning components provide location information of the wearable device so that the care-giver can locate the person.