Author: Derk-Jan Dijk, Professor of Sleep and Physiology and Director of Surrey Sleep Research Centre, University of Surrey

Mafi R/Shutterstock.com For decades, the answer to “how much sleep does an adult need?” has been simple: eight hours. The idea dates back to the mid-19th century when the notion of eight hours of work, eight for recreation and eight for sleep first took hold. But growing evidence suggests that eight hours may not be […]