India has chosen 82 30' as standard meridian and has taken its local time as the standard time of the country.
This has enabled in the uniformity of time in the entire country.
It enables people to have same working hours , with whole country operating at the same time.
It is convenient that one need not set the time while travelling in the country.
It becomes a disadvantage for north eastern states which witness early sunrise.
Thus , it amounts to less daylight to them, as they experience dark early in the evening.