Human African Trypaniosomiasis (HAT) or sleeping sickness is an old disease to be now considered as reemergent. HAT is endemic in 36 sub-Saharan African countries, in areas where tsetse flies are found. The public health importance of HAT is underestimated, but the disease causes severe social disruption in many rural areas. Along the past fifteen years, numerous studies were made, and now, the mechanisms involved in the disease pathogenesis and in the characteristics of sleep-wake disruption become to be better understood. But, since 50 years, when current drugs were introduced, problems regarding HAT chemotherapy have not been solved. Nevertheless, in-depth studies about trypanosome metabolism have permitted to discover new drug targets. Written by specialists who are very experienced in their respective fields, the contributions provide an indispensable tool for practitioners and scientists.