There are no hard statistics on the numbers of these unpaid, volunteer night writers, but Cai Yi, marketing manager at the Jinjiang Literature Site, one of China's hotbeds of online literature with a daily readership of 1 million, estimated that the number has surpassed 10,000 during the past year and continues to rise. "One-quarter of our 650,000 online novels has a time travel theme," said Cai.

Of the website's 7 million registered users, 93 percent are female, and of the thousands of time travel romances on the website, nine out of 10 are the work of female writers ranging from 13-year-old schoolgirls to 40-something mothers and university professors.

"Personally, I am greatly surprised by the passion and perseverance of the authors. Writing thousands of words a day is something that even professionals rarely achieve, not to mention those who have toiled for a whole day," she added.

"While video games may provide an ideal escape for men, women are more than ready to seek refuge in time travel romances, which can also provide relief from overwhelming relationship problems, not least the societal need to marry, suffered by many. These books provide a form of comfort," said Gu Xiaoming, a sociologist at Shanghai Fudan University.

"Exotic charisma"

According to a survey conducted by Shanghai University and the Shanghai Academy of Social Sciences in December, 60 percent of the more than 2,500 respondents would like to travel back to the Tang Dynasty (AD 618-907). Meanwhile, the other favorite eras were the Qing Dynasty and the Spring and Autumn Period (770-476 BC) and the Warring States Period (475-221 BC).

"The results have demonstrated people's yearning to live in what may be perceived as more peaceful, liberated, and economically free times," said Ouyang Guangming, a social science professor at Shanghai University and one of the leaders of the survey.

The Tang Dynasty was one of the most prosperous periods in Chinese history, leaving a great many romantic legends and tales. Meanwhile the Qing princes and princesses also left a legacy of romantic tales.

Cheng Lu, a Beijing-based publisher who has helped dozens of online writers to publish their work, said that time travel romances have come into vogue primarily because they take aspects of modern women's characters, such as independence and perhaps aggression, which are usually taken for granted or even despised in current times, and produce an "exotic charisma".

However, Xiao Chun - a pen name that translates as "Little Spring" - the author of one of China's best-selling time travel stories, said that the success of the books and TV series can only be attributed to the quality of the writing. The success of her story, which has no official English title but can be loosely translated as "Can I Serve Both God and Venus?", ensured that it was subsequently published in book form. To date, it has sold 50,000 copies.