Asked about the inspiration behind his eight-and-a-half-hour 2015 album Sleep, the composer and ambient musician Max Richter said it was pretty simple: Sleep is really important, and he really likes doing it. In that spirit, here’s a mix of contemporary and classic ambient music we feel is perfectly calibrated to smooth the passage between the stresses and noise of waking life and the quiet mystery of dreams. Tap in. Lie down. Tune out. Our editors switch up selections regularly here, so if you hear something you like—or, more pointedly, if you don’t hear it—then add it to your library.