The paper by Blunden and Galland  provides a solid overview of the many complex issues arising in attempts to establish a definition of sleep need. One of the most consistent venues where the issue is raised is in the context of recommendations for “best sleep practices”. Recommendations are often sought by insistent forces in the modern health media: what is best way for an infant or child or teen or adult or parent or retiree to sleep? Sleep scientists are often caught in an awkward position to accede to such requests, knowing that best approximations now available (and the caveats we seek to use as insulation) may be distorted and misrepresented. The core question the authors identify is how to define what it means to have optimal sleep. Shall we measure optimal sleep patterns based on one's experience of sleep per se? Shall we identify optimal sleep by cognitive performance outcomes? Or do we characterize optimal sleep by lapses in performance? Is mood a better outcome? Or metabolic processes? Or temperament outcomes? What is or are the best outcome measures for optimal sleep?