All about daylight saving time after House passes bill to make it permanent
It's not the first time the U.S. has tried to make DST permanent.
Daylight saving time is back in the spotlight after the House of Representatives voted Tuesday to pass a bipartisan bill to make the practice permanent nationwide.
Called the "Sunshine Protection Act of 2025," the bill would end the biannual changing of clocks but would also permit states to opt out.
The bill now heads to the Senate, which passed similar legislation in 2022 -- that measure ended up stalling in the House and was never brought up for a vote -- however, it's unclear if this new version will be adopted.
With the House passage of the latest "Sunshine Protection Act," here's a refresher on what daylight saving time is and why the debate over it continues.
What is daylight saving time?
Daylight saving time is the annual practice of adjusting clocks forward by one hour starting at 2 a.m. local standard time on the second Sunday in March, according to the U.S. Naval Observatory's Astronomical Applications Department.
The practice, which dates back over 100 years after the Standard Time Act went into effect in March 1918, is intended to take advantage of more sunlight during the day and save on energy consumption.
Daylight saving time ends on the first Sunday in November, when the clocks are turned back one hour, reverting to standard time.
The start and end dates of daylight saving time in the United States were established by the Energy Policy Act of 2005 and have been observed since 2007.
What happens if the U.S. makes daylight saving time permanent?
If daylight saving time becomes permanent, clocks will no longer have to be adjusted one hour ahead every spring.
Does the sun rise earlier or later with daylight saving time?
Sunrises would remain largely the same during the summer months for most people in the U.S., if daylight saving time were made permanent.
In the winter months, however, the sun would appear to rise one hour later, as late as nearly 9 a.m. in some places, at certain parts of the year, according to Time and Date.
The last time the U.S. implemented permanent daylight saving time, in 1974 -- as a way to save energy during the 1973 oil crisis -- it quickly became unpopular, with many parents objecting to sending their children to school in the dark. The legislation was later repealed that same year.
Which states do not follow daylight saving time?
Daylight saving time is not a universal practice and some states and territories already follow a different schedule.
Arizona (aside from the Navajo Nation), Hawaii, American Samoa, Guam, Northern Mariana Islands, Puerto Rico and the U.S. Virgin Islands currently do not observe daylight saving time.
Do other countries follow daylight saving time?
Although it is observed in some parts of the world, primarily in North America, the U.K., and Europe, not all countries have adopted or maintained the practice of daylight saving time.
in 2022, Mexico voted to end daylight saving time in most parts of the country, as the Associated Press reported at the time.
What is the health impact of daylight saving time?
Daylight saving time can impact one's health due to changes in sleep schedules.
"Small changes in sleep, even small decreases, can detrimentally affect your health, increasing stress hormones," ABC News medical correspondent Dr. Darien Sutton explained on "Good Morning America" in 2025. "That increases our risk of heart attacks and strokes, principally among women and older adults in the first two days after this shift change."
To minimize the effects of daylight saving time on one's health, Sutton recommended making a few adjustments, including modifying one's bedtime 15 to 20 minutes earlier than usual, maintaining sleep consistently over time, and avoiding alcohol.
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