Anecdotally, my grandfather, who was bedridden with advanced dementia for the last years of his life, tended to be far more lucid before breakfast than at any other time of day. Knowing of the type three diabetes hypothesis, I surmised that this could be, at least partially, a result of the overnight fast, during which his metabolism likely stabilised to a degree, although it's unlikely that he'd have fully entered ketosis. I suggested that he be switched to a ketogenic diet, at least for a few weeks, as a trial, but this was considered to be a ridiculous idea by his carers, and was never done, unfortunately.