I had a similar discovery with sleep myself like that. I had been suffering from un-diagnosed severe complex sleep apnea for as best as we can figure 5-10 years. once starting sleep with a BiPAP machine to help with the breathing I went from having no REM sleep and no dreams to having them all the time. After about the first month I could finally remember what happened the day before clearly and without issue. The dramatic change did actually swing me a little more towards depression for a while simply because I could finally understand what I had been missing for so long and that there was nothing I could do to get it back. It was definitely an interesting experience.