Internet of Things is a fast growing technology and a network of devices in which everything (smart objects or smart devices) are associated to the internet for effective exchange of information between these connected objects. Internet of Things (IoT) serves as a method for healthcare and acts as an essential part in broad range of real-time healthcare monitoring applications. Previous work shows networked sensor devices, either equipped on the body or embedded inside living being or a camera, make possible in gathering real-time information to evaluate physical and mental health state of the patient by collecting body temperature, blood pressure, patient's image, etc. Communicating this collected real-time data to the doctor, making accurate assessment on the data gathered and notifying the patient is challenging task in the IoT. The architechture of Internet of Things comprises of three layers, and it is the network of devices embedded with sensor, software, and electronics, enabling this device to communicate with each other and exchange data over a computer network. The IoT-based real-time healthcare systems are highly vulnerable to cyber-attacks as the numbers of sensors are deployed in an unprotected network. These may even introduce the attacks, which cannot be monitored and controlled. This paper attempts to review the previous work done and a new scheme has been proposed, the new lightweight authentication protocol for smart real-time healthcare. The proposed scheme requires implementation with the authentication protocol. It is important to satisfy the major parameters of security: confidentiality, integrity, authentication, and access control. In this paper our focus is on the authentication of devices.