Try the classic from 1976 to get an idea of what thinking on this was at the time funding for sleep science started: Some Must Watch While Some Must Sleep (Deme

Try the classic from 1976 to get an idea of what thinking on this was at the time funding for sleep science started: Some Must Watch While Some Must Sleep (Dement, 1976, 1978): https://archive.org/details/somemustwatchwhi00dem_3n2 https://archive.org/details/somemustwatchwhi00dem_3n2 (1978 edition)