Fall is here, which means the end of daylight saving time is also near.

Since the Energy Policy Act of 2005 was passed, daylight saving time in the United States begins annually on the second Sunday in March and ends on the first Sunday in November.

When daylight saving time begins in March, the clocks jump forward one hour, and when it ends in November, the clocks jump back one hour.

Here are five questions answered about the upcoming time change.

1. When does daylight saving time end in 2024?

This year, daylight saving time ends on Sunday, November 3, with the clocks going back one hour at 2 a.m

The change will make it darker earlier in the evening in the United States.

2. Do we gain or lose an hour of sleep when we ‘relapse’?

When the clocks “fall back” at the end of daylight saving time, people get an hour of sleep.

For example, on Sunday, falling asleep at 10 p.m. will be like falling asleep at 9 p.m. once the clock goes back an hour at 2 a.m.

On the other hand, when the clocks “jump forward” in March, at the start of daylight saving time, people lose an hour of sleep.

3. What is daylight saving time and why did it start?

According to the US Naval Observatory’s Astronomical Applications Division, daylight saving time was introduced in the US in 1918 with the passage of the Standard Time Act.

The time change was implemented as a way to maximize daylight hours to help save on energy consumption during World War I.

In subsequent decades, lawmakers have made unsuccessful attempts to repeal daylight saving time nationally, and some individual states and cities have reverted to non-daylight saving time hours.

In 1966, Congress passed the Uniform Time Act, which established uniform daylight saving time across the U.S., according to the U.S. Department of Transportation, the federal agency that oversees time zones.

Under the Uniform Time Act of 1966, states that observe daylight saving time must follow the federally mandated start and end dates.

States can also exempt themselves from observing daylight saving time under state law, the DOT said.

In 2022, the U.S. Senate unanimously passed a measure, the Sunshine Protection Act, that would have made daylight saving time permanent in the U.S., but the legislation was never brought to a vote in the U.S. House of Representatives.

4. Which states are not following daylight saving time changes?

Hawaii and Arizona – with the exception of the Navajo Nation – are the only two states in the country that do not participate in daylight saving time, according to the DOT.

Additionally, five U.S. territories also do not participate in daylight saving time: American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the Virgin Islands.

5. What are the potential health risks of daylight saving time?

Some health experts claim that daylight saving time disrupts the body’s natural circadian rhythm.

In 2023, the American Academy of Sleep Medicine formed a coalition to advocate for state and federal legislation making standard time permanent in the US. Other organization members include the National Sleep Foundation, Save Standard Time, Sleep Research Society, and Society for Research on Biological Rhythms.

The shift in time has been linked to an increase in heart attacks, strokes, abnormal heart rhythms, sleep disruption, mood disorders and even suicide, according to research published in the Journal of Clinical Sleep Medicine.

Dr. ABC News medical contributor Darien Sutton recommends that before changing the clock, people gradually adjust their bedtime to accommodate the change.

Sutton said it’s also okay to take a nap if you feel fatigued by the time change, but try to limit the nap to 30 minutes and do it before 3 p.m.

Finally, Sutton said that when the clocks “fall back,” it is important to increase exposure to sunlight during the day, especially in the morning, and to limit alcohol and caffeine intake.

Dr. Avish K. Jain, DO, physician at Cooper University Hospital, medical contributor to the ABC News Medical Unit, contributed to this report.