Once she gets home from work, the 26-year-old spends four hours catching up on Chinese drama serials and variety shows on cable television till the wee hours. She wakes up at 7am the next day to go to work.

Ms Gao is among a growing tribe of young adults who are deliberately choosing to sleep later and for fewer hours, reported Mypaper.

The trend is worrying sleep specialists and parents. Such sleeping habits can be harmful to health, said Dr Kenny Pang, ear, nose and throat consultant and sleep specialist at Pacific Sleep Centre.

He warned that insufficient rest can lead to poor concentration, decreased productivity at work and increased irritability.

He sees at least 50 new cases of patients who suffer from 'junk sleep' yearly and that number has been rising for the past two years.

He said junk-sleep patients have poor-quality sleep, as they would rather expend their time and energy on using electronic gadgets, such as getting on their computers and watching TV, than getting more rest. Most develop the habit of sleeping later and less during their school years, when they study late into the night.

He added that in more than half of the cases he sees, patients have even developed issues such as depression and relationship problems, and entertain suicidal thoughts.

When told of the consequences, many night owls said they would stick to their sleeping patterns. Civil servant Alvin X, 28, who sleeps for only five hours a day, simply said: 'I'm used to feeling tired.'

Still, others know that they would not be able to sustain this lifestyle for too long. Miss Ng said: 'I want to sleep earlier because it's unhealthy. Besides, the circles around my eyes are getting too dark for my liking.'