Poor Sleep Makes People Poor: The Costs of India Standard Time
After Independence, India adopted a single time zone for the entire country. India spans as much 1,822 miles in the East-West direction or 29 degrees longitude. If India followed the convention of a new time zone every 15 degrees it would have at least two time zones. With just one zone the sun can rise two hours earlier in the East than in the far West.
In an original and surprising paper, Maulik Jagnani, argues that India’s single time zone reduces the quality of sleep, especially of poor children and this reduces the quality of their education. Why does a nominal change impact real variables? The school day starts at more or less the same clock-hour everywhere in India but children go to bed later in places where the sun sets later. Thus, children in the west get less sleep than children in the east and this shows up in their education levels and later even in their wages!
I find that later sunset causes school-age children to begin sleep later, but does not affect wake-up times. An hour (approximately two standard deviation) delay in sunset time reduces children’s sleep by 30 minutes. I also show that later sunset reduces students’ time spent on homework or studying, and time spent on formal and informal work by child laborers,while increasing time spent on indoor leisure for all children. This result is consistent with a model where sleep is productivity-enhancing and increases the marginal returns of study effort for students and work effort for child laborers.
The second part of the paper examines the consequent lifetime impacts of later sunset on stock indicators of children’s academic outcomes. I use nationally-representative data from the 2015 India Demographic and Health Survey (DHS) to estimate how children’s education outcomes co-vary with annual average sunset time across eastern and western locations within a district. I find that an hour (approximately two standard deviation)delay in annual average sunset time reduces years of education by 0.8 years, and children in geographic locations with later sunset are less likely to complete primary and middle school.
Addendum: The importance of sleep and coordination of sleep with circadian rhythms is also illustrated by the phenomena of teenagers who get more sleep and do better in school when school opening is better timed with adolescent sleep patterns. As a result, we are seeing a movement to push school opening times later for teenagers. Perhaps India will adopt a second time zone.