The denomination of “personalized medicine” has been used in Sleep Medicine, especially in the context of obstructive sleep apnea syndrome (OSAS). It refers to an “umbrella term”, which seems insufficient to conceptually define the extent of the field. Regarding the convergence between personalized medicine and Sleep Medicine, this article proposes a clarification to the concepts around personalized medicine by proposing a distinction between precision medicine and stratified medicine in OSAS. Precision medicine seeks to integrate molecular and biological research with the clinical data of each patient to develop a more precise “molecular taxonomy” of diseases by identifying endotypes related to biomarkers. The reference author in this field of OSAS is Eckert. Indeed, Eckert highlighted three potentials “endotypes” of OSAS (impairment in pharyngeal dilator muscle control and function during sleep; increased propensity for awakening during airway narrowing with low respiratory arousal threshold; respiratory control instability with high loop gain). Stratified medicine seeks to integrate research on big data to develop clusters in order to define new phenotypes by identifying sets of indicators. Especially, phenotyping allows us to set up an optimized prevention and therapy due to an appropriate adaptation to the specific characteristics of a subgroup. Thus, phenotyping improves diagnostic, prognostic and follow-up strategies. The reference author in this field is Zinchuk who does not use the term stratified medicine (but use rather precision medicine). This author highlighted six potentials “phenotypes” of OSAS (called subtypes A to F). The terminology used in this article is not intended to be definitive, but offers a framework for clarifying the concepts involved, the research programs initiated and the representations of researchers. The ambitions of a robust research program for OSAS would require a pairing of the precision and stratification approaches, by building an integrative framework for the future of Sleep Medicine. This program allows us to define phenotypes related to mechanically explanatory endotypes, and to define endotypes related to clinically useful phenotypes.