It has come to our attention that the American College of Chest Physicians CD, “Sleep: Study Lessons in Education; product code 6633” has misinterpreted some of the findings from the Sleep Heart Health Study (SHHS). In the section, “Sleep-Disordered Breathing Events: Question 5, A. Hypopnea,” it is stated that “In fact, the scorers of the polysomnographies in the SHHS required a 4% oxyhemoglobin desaturation in order to score either apneas or hypopneas, because they could not achieve inter-rater reliability of apneas and hypopneas otherwise. Thus, the SHHS outcome data are essentially based on oximetry.” These two sentences are incorrect. Although it is true that the SHHS requires a 4% oxygen desaturation as one of its criteria to identify a hypopnea in most of its publications, this desaturation criterion was not chosen because we were unable to otherwise obtain interrater reliability using other criteria. Rather, a 4% oxygen desaturation was chosen because we wished to be consistent with the scoring criteria used by the Wisconsin Sleep Cohort so that comparisons could be made between the studies. Moreover, in the article by Whitney et al,1 we demonstrated that the intraclass correlation coefficients using various oxygen desaturation criteria were all > 0.90.