Wireless sensor network (WSN) technologies is considered as one of the main research areas in computer science. These WSNs comprise tiny wireless computers that sense, process, and communicate environmental stimuli, including temperature, light, and vibration. WSNs have been under rapid development and has become essential in various domains like industrial operations (factory, production, supply chains) and health care (home monitoring, biomedical, food safety), So, the main objective of this paper is to provide a quick overview of current developments and future trends of research on WSN for continuous monitoring of patients as a major application of WSN in the field of healthcare systems. Finally, this paper assure that the application of the Wireless Sensor Networks in healthcare systems is mainly divided into three categories: monitoring of patients in clinical settings, home and elderly care center monitoring for chronic and elderly patients, and collection of long-term databases of clinical data. In these three categories, the sensors allow vast amounts of data to be collected and mined for next-generation clinical trials. Data will be collected and reported automatically, reducing the cost and inconvenience of regular visits to the physician. Therefore, many more study participants may be enrolled, benefiting biological, pharmaceutical, and medical-applications research.