Updated U.S. census benchmark sleep dataset v1.1

We previously documented and released a benchmark dataset for machine learning research on sleep stage classification [1]. Subsequently, it was pointed out in a preprint [2] that some recordings in the National Sleep Research Resource [3] include only binary wake-sleep annotations, instead of full sleep stage scoring using the Rechtschaffen and Kales (R&K) [4] or American Academy of Sleep Medicine (AASM) [5] standards. Because wake-sleep labels are an ontological mismatch and not just label noise, they do not belong in a dataset designed for full sleep stage classification. Therefore, we have updated our benchmark dataset (henceforth known as benchmark v1.0) to replace 16 recordings with suitable recordings from age- and sex-matched subjects, while all other dataset selection criteria and distributions have been preserved. Additionally, the total number of recordings and the composition of the training, validation, and testing sets remain unchanged. While this update is a minor revision, we want to distinguish its use from v1.0, and therefore have titled this update as benchmark v1.1. The file listings are provided on the GitHub repository (https://github.com/adammj/ecg-sleep-staging/).