	Introduction

Daylight Saving Time (DST) is a period of the year between spring and fall when clocks in most parts of the United States are set one hour ahead of standard time. Congressional interest in the potential benefits and costs of DST has resulted in changes to DST observance since it was first adopted in the United States. The Calder Act or the Standard Time Act of 1918

In 1918, Congress passed an act to provide standard time for the United States (also known as the Calder Act and the Standard Time Act of 1918). If a state chose to observe DST, the time changes were required to begin and end on the established dates. 92-267) to allow states that were split between time zones to exempt either the entire state or that part of the state lying within a different time zone. In 2005, Congress enacted the Energy Policy Act of 2005 ( P.L. 109-58 ). Section 110 of this act amended the Uniform Time Act, by further changing DST to begin the second Sunday in March and end the first Sunday in November; this DST period remains in effect today. Congress has required several agencies to evaluate the effects of DST. In terms of primary energy consumption, this represents approximately 0.02% of total U.S. energy consumption in 2007. Health

Several studies have examined potential health effects related to the semiannual changing of the clock per DST. Harrison (2013) reviewed the effect of DST on sleep, and found that data from the spring and fall transition periods suggest a cumulative effect of sleep loss. These include efforts to establish permanent DST as well as efforts to establish permanent standard time. Several states have also introduced legislation to study the effects of DST or the effects of changing the observance of DST. Most of the legislative proposals in recent years have not passed. One exception is Florida's H.B. 1013, which would institute year-round DST in Florida "if the United States Congress amends 15 U.S.C. s. 260a to authorize states to observe daylight saving time year-round." Potential Issues for Congress

Congress may consider whether to make additional changes to DST observance or standard time. In the 115 th Congress, four bills have been introduced that would make changes to standard time. On March 12, 2018, the House Committee on Energy and Commerce sent a letter to the Department of Transportation requesting updated information related to DST and standard time "to more fully appreciate the various policy factors associated with changing between Standard and [DST]."
Daylight Saving Time (DST) is a period of the year between spring and fall when clocks in most parts of the United States are set one hour ahead of standard time. The time period for DST begins on the second Sunday in March and ends on the first Sunday in November. The beginning and ending dates are set in statute. Congressional interest in the potential benefits and costs of DST has resulted in changes to DST observance since it was first adopted in the United States.
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 (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 potential effects to national energy consumption of an extended DST, 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 in specific subgroups.
Only Congress can change the length of the DST observance period; however, several states have proposed legislation to change their observance of DST. These efforts include proposals to effectively establish permanent DST and proposals to establish permanent standard time. Most of the proposals have not passed. One exception is Florida's HB1013, which would institute year-round DST in Florida "if the United States Congress amends 15 U.S.C. s. 260a to authorize states to observe daylight saving time year-round."
Congress may consider whether to make additional changes to DST observance or standard time. Several bills have been introduced in the 115th Congress that would make changes to standard time to effectively implement year-round DST. On March 12, 2018, the House Committee on Energy and Commerce sent a letter to DOT requesting updated information related to DST and standard time.