May 22, 2022

Timely! All About Daylight Savings Time (CRS Report)

From the Congressional Research Service.

From the Report’s Summary:

Daylight Saving Time (DST) is a period of the year between spring and fall when clocks in mostparts of the United States are set one hour ahead of standard time. DST begins on the second Sunday in March and ends on the first Sunday in November. The beginning and ending dates areset in statute. Congressional interest in the potential benefits and costs of DST has resulted i

In changes to DST observance since it was first adopted in the United States in 1918.The United States established standard time zones and DST through the Calder Act, also known as the Standard Time Act of 1918. The issue of consistency in time observance was further clarified by the Uniform Time Act of 1966. These laws as amended allow a state to exempt itself—or parts of the state that lie within a different time zone—from DST observance. These laws as amended also authorize the Department of Transportation (DOT) to regulate standard time zone boundaries and DST. The time period for DST was changed most recently in the Energy Policy Act of 2005 (EPACT 2005; P.L. 109-58).

Congress has required several agencies to study the effects of changes in DST observance. In 1974, DOT reported that the potential benefits to energy conservation, traffic safety, and reductions in violent crime were minimal. In 2008, the Department of Energy assessed the effects to national energy consumption of extending DST as changed in EPACT 2005 and found a reduction in total primary energy consumption of 0.02%. Other studies have examined potential health effects associated with the spring and fall transition to DST and found a cumulative effect of sleep loss and increased risk for incidence of acute myocardial infarction (heart attacks) in specific subgroups.

Table of Contents

Direct to Full Text Report
18 pages; PDF.

About Gary Price

Gary Price ( is a librarian, writer, consultant, and frequent conference speaker based in the Washington D.C. metro area. Before launching INFOdocket, Price and Shirl Kennedy were the founders and senior editors at ResourceShelf and DocuTicker for 10 years. From 2006-2009 he was Director of Online Information Services at, and is currently a contributing editor at Search Engine Land.