This paper presents an independent sleep scheduling protocol for energy-efficient wireless body area networks. We designed the proposed protocol based on the IEEE 802.15.6 standard that is flexible to cover various application requirements for WBAN. The target of the proposed protocol is applications that generate aperiodic and intermittent traffic. Thus, the node providing these applications wakes up only when a new event occurs. We perform the numerical analysis and the simulation to compare the IEEE 802.15.6 without and with the independent sleep scheduling protocol. The results show that the proposed protocol increases energy-efficiency in case of large data size as well as long data occurrence interval.