This research was supported by contracts HHSN268201500003I, N01-HC-95159, N01-HC-95160, N01-HC-95161, N01-HC-95162, N01-HC-95163, N01-HC-95164, N01-HC-95165, N01-HC-95166, N01-HC-95167, N01-HC-95168, and N01-HC-95169 from the National Heart, Lung, and Blood Institute (NHLBI), and by grants UL1-TR-000040, UL1-TR-001079, and UL1-TR-001420 from the National Center for Advancing Translational Sciences. The MESA Sleep Study was supported by NHLBI grant HL56984. Dr. Huang was supported by K01HL143034 and Dr. Redline was supported by R35HL135818 from the NHLBI of the National Institutes of Health (NIH). The funders had no role in the design and conduct of the study, in the collection, analysis, and interpretation of the data, and in the preparation, review, or approval of the manuscript. Dr. Redline has received research grants and consulting fees from Jazz Pharma; and has received a consulting fee from Respircardia Inc. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.