This book provides a systematic treatment of the theoretical foundation and algorithmic tools necessarily in the design of energy-efficient algorithms and protocols in wireless body sensor networks (WBSNs). These problems addressed in the book are of both fundamental and practical importance. Specifically, the book delivers a comprehensive treatment on the following problems ranging from theoretical modeling and analysis, to practical algorithm design and optimization: energy-efficient clustering-based leader election algorithms in WBSNs; MAC protocol for duty-cycling WBSNs with concurrent traffic; multi-channel broadcast algorithms in duty-cycling WBSNs; and energy-efficient sleep scheduling algorithms in WBSNs. Target readers of the book are researchers and advanced-level engineering students interested in acquiring in-depth knowledge on the topic and on WBSNs and their applications, both from theoretical and engineering perspective.