There is no reason for daylight savings time. Changing clocks by an hour at different times each year results in nothing but a period of jet lag for those residents affected.
Daylight savings time is an outdated tradition based on an archaic belief that we will save energy. Most people I know stay awake long after the sun goes down when we "fall back" and rely on lights during those hours.
Time is relative. If people need to be awake when the sun is up, they will out of necessity. All of China has a single time zone. Time is just a reference point by which people can communicate when events will or have happened.
Most people have jobs that rely on zero sunlight where the lights are always on. Net savings of rolling back or rolling forward the clock is zero.