I've had jetlag-induced hypo/manias. Not fun. The way that time sometimes seems artificial or arbitrary during a mania is [in my experience] mirrored in many ways by how off-putting it is to be 8 hours out of sync after a hop across the pond. 8AM doesn't feel 'real' when your body wants dinner.

The quote from Binswanger sounds just about right to me. Mania brings paradoxical views about the future:

On one hand, I'd be writing down the titles of dozens of books that I want to read and mountains of things that I'd want to do, etc. I wrote down enough plans to keep me busy for years.

On the other hand, I had a sharp awareness that just because I was alive now didn't mean I would be tomorrow, or next week, or next year. Not that I was suicidal or thought that something bad was going to happen. It's just that in a baseline mental state I don't think much about impermanence/death, and kind of take for granted that my existence will continue. During mania the "live every day as though it's your last" cliché actually became internalized. I would move on my goals and passions instantly since I might never get the chance otherwise - the normally-natural act of 'putting something off for tomorrow' felt inconceivable.

I think there's probably a happy medium between being blasé about life (and taking for granted its continuation) and literally living every day in the absolute moment because it could be the last. I think every person on the planet has to find a spot somewhere on that scale, it's just that bipolar gives me an extra push and shove around it sometimes.