A staff of an e-commerce division takes a nap at his desk at KSW Food Company's headquarters in Suzhou, Jiangsu province, at 5 am, on Nov 11, 2015. [Photo/IC]

KSW Food Company's headquarters were brightly lit on the eve of Singles Day, as around 400 staff pulled all-nighters for the annual 24-hour online shopping festival.

The company saw its sales exceed 1 million yuan ($157,172) within the first half hour after the shopping spree started on Nov 11.

Ever since China's biggest e-commerce giants turned the day into a once-in-a-year bargain frenzy, vendors have cashed in, busy with promotion and stocking inventory.

The country's online retail sales are expected to rise to 10 trillion yuan in 2020 with the penetration rate doubling from the 2014 level to 22 percent, according to a report released on Monday by Bain & Company and Alibaba.