It was a chilly April night in 2020 in Orange County, California. The clock read 3.20am (7.20pm Singapore time) and Zang couldn't sleep, plagued by insomnia since the state issued a stay-at-home order on March 19 amid a Covid-19 outbreak. The then-22-year-old had come to the US from China in 2016 to pursue a bachelor's degree, and was a month.