Time Zones and the Economics of Clocks

Why India has a single time zone, why some argue for two, and how clock time affects productivity, sleep and energy use.

Clock time is a coordination tool, and it has economic effects.

One time zone for India

India uses Indian Standard Time (IST), 5 hours 30 minutes ahead of UTC, across the whole country.

The problem

India stretches nearly 3,000 km east to west. In the Northeast, the sun rises and sets much earlier than in Gujarat.

In Assam, the sun can set around 4:30 to 5 pm in winter, while offices run on IST.
Daylight is wasted in the morning and more electricity is used in the evening.

Chaibagan time

Assam’s tea gardens have long used a local “tea garden time” an hour ahead of IST.

Calls for two time zones

Some have proposed a separate time zone for the Northeast to save energy and improve productivity. The government has kept a single zone, citing coordination and the risk of confusion.

Research on sunset times

A study of India found that later sunset times were associated with less sleep, especially among poorer children, and lower educational outcomes, highlighting how clocks affect well-being.

Daylight saving

India doesn’t use daylight saving time. Many countries do, though its energy benefits are debated.

The early sunset

In Guwahati in winter, it gets dark before offices close. Shops and offices switch on lights for hours, while morning daylight at 5 am goes unused.

Thinking time zones are only about geography

They affect energy, sleep and productivity.

Key takeaways

India uses one time zone, IST.
The Northeast wastes morning daylight.
Assam's tea gardens use a local time.
Clock time affects energy, sleep and learning.