I have a mild fear of losing consciousness. It's mostly related to anesthesia. I often have nightmares of being anesthetized in preparation for surgery. The second part of Beating the Heat originally had Sarah awake but unable to move or speak as Sunshine attempted some anatomically ignorant healing inspired by said nightmares. It got really dark really fast, so I scrapped the idea.
When the depression gets really bad that fear blows up into hypnophobia (fear of falling asleep). I'll jolt awake hyperventilating just as I start nodding off. I also find the fact that we spend a third of our lives asleep to be existentially unsettling. That largely inspired the yinrih's torpor cycle.
Lodestar is my idea of the ideal older sibling. Iris is the idealist in me, Pascal is the (much louder) pessimist in me. Stormlight is my job as a character. Sunshine as a person doesn't have a whole lot of inspiration behind her, but I was interested in the inner workings of the human body as a kid, and the ubiquitous “Fantastic Voyage” plot where characters would shrink down and enter someone's body to fix or retrieve something featured heavily in my imagination, which in turn inspired the idea of micro mechs, an arguably more plausible and inarguably more sensible alternative to shrinking down and going in yourself. Sunshine's name was inspired by a coworker of mine who went by that name. I'm not sure if it was her legal name or a nickname, but I remember being initially put off by it only to remind myself that it perfectly fits my criterion for an ideal name in that it holds meaning rather than being a stylish collection of phonemes. I also personally love literal sunshine, as I have seasonal affective disorder. So the name grew on me.
Tod is also pretty light on inspiration.