We thank Fan Yuan, and coll [1] and Linru Zhong and coll [2] for their interest in our study [3]. They add pertinent reflections and critical analysis of our study. We are aware of the unavoidable limitations of retrospective studies like ours which had been clearly stated [3]. While we agree with some comments by authors of both letters [1,2] when referring to the highest-level settings, we are pushed to some general considerations regarding the wide application of sleep studies in real-world setting.
