At the bottom of this article it references a 2003 study in the journal Sleep that finds that the more tired you are, the less tired you feel. https://www.scientificamerican.com/article/fact-or-fiction-can-you-catch-up-on-sleep/ However, they haven't put a link to it. I've google searched a bit and I can't find it. Has anyone heard about this before? Or perhaps your googling skills for scientific studies are more advanced than mine? If it's true, it could explain why many of us feel tired all day and then feel most awake just before going to bed.