To learn about spaced repetition and "sleeping time", please visit
https://www.trainchinese.com/v2/viewExplainTrainingAlg.php?rAp=0. If you log into your account on our website trainchinese.com, under More..., Settings, you have various options to adjust your training settings, set up Advance wake up, and/or Postpone wake up. Please explore a little and let us know if you have further questions. Thank you!