Daylight Saving Time.

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 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 (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, since 2015, at least 39 states have proposed legislation to change their observance of DST. These efforts include proposals to exempt a state from DST observance--which is allowable under existing law--and proposals that would effectively establish permanent DST--which would require Congress to amend the Uniform Time Act of 1966. Most of the proposals have not passed. Three states have enacted permanent DST legislation: Florida, Washington, and Tennessee. Congress may consider whether to make additional changes to DST observance or standard time. Several bills have been introduced in the 116th 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. On June 20, 2018, DOT informed the committee that it had initiated a literature review of the issue and would share the results with the committee, but as of June 2019 this has not been submitted. [ABSTRACT FROM AUTHOR]