Investigating the lagged relations between sleep duration and achievement, and whether they are moderated by student characteristics. **Note: This is an updated preregistration to the one that was posted in the project files on 08/02/2019. Given the length of time that has passed since the initial preregistration and our better understanding of the RI-CLPM, we felt it was necessary to update the preregistration. The prior version contained references to a different model that evaluated kindergarten bedtime; for simplicity, we are no longer evaluating a model that includes kindergarten bedtime. The prior version also contained a number of inaccuracies about the RI-CLPM (e.g., suggesting the use of MODINDICES to improve model fit; this option is unavailable with the RI-CLPM and the model typically fits the data very well).