That first night, driving home from work, you'd flipped the radio to the news in time to catch part of the announcement.
"-fternoon in Forest Park. Witnesses claimed she stepped out from the tree line, completely naked, and began shouting about light pollution."
"Yeah she seemed really upset about something. Screaming about people's lights being on all night and traffic noises I think? Then she started shouting something about no more men at night? I dunno, maybe she was a drugged out sex worker or something?"
"After a few minutes of shouting at passers by in the park, the woman apparently just walked backwards to the trees, and has not been sighted since. Police recommend everyone in the area be alert and keep doors and windows locked."
You hadn't listened any further, not that it would have helped. You'd pulled into your driveway, and just stepped out of your car, as the sun began to set, and you began to change for the first time. Your bones cracked. You doubled over in pain. It seemed as if your clothes were growing all around you when in reality it was you that was shrinking. All around you were horrible screams. It wasn't just you, everyone was transforming all at once. Ceasing to be human. There were sounds of breaking glass, loud predatory shrieks. Even if you hadn't been shrunken and transformed, you'd have been terrified. As it was, fresh instincts urged you to scamper away, seeking shelter in the knothole of a nearby tree. Your memory of the rest of that night was a bit muddled. You'd become a squirrel, you're fairly certain. Fluffy tail, small body. You somehow slept through most of the night after a bit of exploration of your new body, when you weren't too paralyzed with fear to move.
You didn't sleep much past dawn that night. As soon as the sun began to rise, you started to revert, and the knothole became far too small quite quickly. You were lucky it hadn't been too high up, as you tumbled out, falling to the ground. Again, the transformation was a painful process. Your skeleton rearranging itself and your whole body stretching out. There you'd been, lying naked on the ground by a tree, after the strangest night of your life. You weren't alone in that either. All around you embarrassed neighbors dashed back to their homes after spending the night as various other creatures. Personally you dashed inside, heading straight for your computer to try and learn more.
The whole day, the world was tossed into chaos. People were desperate to learn what happened, or how. Infrastructural problems were rampant as essentially all of humanity had disappeared as soon as the sun had set. There'd been casualties as well. Some had transformed while behind the wheels of their vehicles, leading to widespread accidents. Many people were missing. A few had horrifying memories, having transformed into nocturnal predators and taking a meal, unsure if their prey had been human by day.
You'd still been in your research panic when the sun went down again. This time the change was far more painful and bizarre. Extra legs sprouted from your midsection and wings from your back. Big bushy antennae above your eyes, which worked quite differently. You suspect you'd transformed into a moth, or some sort of housefly. Instinct compelled you to spend the night trying to escape, and you just kept alternating between bouts of rest and frantically smacking into every window until dawn restored your humanity.
That was this morning. You've spent half the day already doing more research, and had little luck. The government was trying to focus on getting everyone to continue going to work in spite of everything. Nobody really knew anything, but you figured that news broadcast was about some sort of actual witch or forest spirit who'd cursed all of humanity. It did at least seem that when people changed, they became something suited to their environment, so that was something. You could maybe get to the roof of a large building, spend the night as a bird? Set out some pet food for yourself? There were only a couple hours before the sun would set again, you had to make the most of it.