Why iPhone, Android, Fitbit, Alexa, TVs automatically update when daylight saving time ends

Jennifer Sangalang, Palm Beach Post
·8 min read

In less than a month, daylight saving time will be over for 2023. You may not be ready for the end of daylight saving time. But our iPhone and Android devices are.

At 2 a.m. ET Sunday, Nov. 5, the first Sunday in November, daylight saving time ends, and we'll have to change our wall clocks and some car clocks back by one hour or "fall back." We'll revisit changing wall clocks and car clocks in March when daylight saving time 2024 begins. At 2 a.m. ET Sunday, March 10, the second Sunday of March, we'll "spring forward" or set our clocks ahead by one hour.

But what about our phones and computers? Apple Watch? Fitbit? Alexa? The Kindle? Nope, there's no need to change the time on those for daylight saving time.

Below are questions and answers about daylight saving time and how our phones and electronic devices measure and display time.

What is daylight saving time?

According to timeanddate.com, "daylight saving time is the practice of setting the clocks one hour ahead of standard time to make use of more sunlight in the spring, summer, and fall evenings. Daylight Saving Time (DST) is used to save energy and make better use of daylight. It was first used in 1908 in Thunder Bay, Canada."

Daylight saving time became a national standard in 1966 when President Lyndon B. Johnson signed the Uniform Time Act, which was established as a way to continue to conserve energy. The thinking was, if it's light out longer, that's less time you'll need to use lights in your home.

What are the current rules of daylight saving time?

According to the National Institute of Standards and Technology of the U.S. Department of Commerce, these are the current rules:

The rules for daylight saving time changed in 2007 for the first time in more than 20 years. The new changes were enacted by the Energy Policy Act of 2005, which extended the length of DST in the interest of reducing energy consumption. The rules increased the duration of DST by about one month. DST is now in effect for 238 days, or about 65% of the year, although Congress retained the right to revert to the prior law should the change prove unpopular or if energy savings are not significant.

  • Daylight saving time in the U.S. begins at 2 a.m. the second Sunday of March (at 2 a.m. the local time skips ahead to 3 a.m. so there is one less hour in that day)

  • Daylight saving ends at 2 a.m. the first Sunday of November (at 2 a.m. the local time becomes 1 a.m. and that hour is repeated, so there is an extra hour in that day)

Daylight saving time is here to stay. Even though US Senate OK'd Sunshine Protection Act, Florida will still fall back, for now

Why do we change clocks at 2 a.m. Sunday for daylight saving time?

For fall back and spring forward, changing our wall clocks for daylight saving time begins and ends at 2 a.m. (Your mobile devices, computers, tablets, smart watches, exercise trackers and digital devices automatically change during daylight saving time.) A 2019 story in Time magazine explains why the changes occur at 2 a.m., "The reason daylight saving time starts at 2 a.m., rather than midnight, is all thanks to the railroads: Amtrak, specifically. When the country first experimented with daylight saving time in 1918 during World War I, there were actually no trains that left New York City at 2 a.m. on a Sunday.

"There were even fewer freight trains in the early 20th century than there are today, so it made the most sense — changing the clocks at 2 a.m. would not be disruptive," the article states.

Where do our phones, computers, laptops, tablets get the time from?

According to NIST, the digital clocks on our computers and phones get their time from atomic clocks. Also, GPS is used to help tell time.

Global Positioning System's federal site, gps.gov, explains how: "Each GPS satellite contains multiple atomic clocks that contribute very precise time data to the GPS signals. GPS receivers decode these signals, effectively synchronizing each receiver to the atomic clocks. This enables users to determine the time to within 100 billionths of a second," the site states. GPS is maintained by the U.S. Space Force. GPS.gov is maintained by the National Coordination Office for Space-Based Positioning, Navigation and Timing.

What is an atomic clock?

An atomic clock is a certain type of clock that measures the resonant frequency of atoms. NASA explains how an atomic clock works in space and on Earth: "Most modern clocks, from wristwatches to those used on satellites, keep time using a quartz crystal oscillator. These devices take advantage of the fact that quartz crystals vibrate at a precise frequency when voltage is applied to them. The vibrations of the crystal act like the pendulum of a grandfather clock, ticking off how much time has passed.

"Atomic clocks combine a quartz crystal oscillator with an ensemble of atoms to achieve greater stability. NASA’s Deep Space Atomic Clock," the site states, "will be off by less than a nanosecond after four days and less than a microsecond (one millionth of a second) after 10 years. This is equivalent to being off by only one second every 10 million years."

NIST operates an atomic world clock and manages the real-time federal site, time.gov (not to be confused with the newsmagazine Time.com). This atomic clock displays:

  • Chamorro Standard Time

  • Samoa Standard Time

  • Hawaii Standard Time

  • Aleutian Daylight Time

  • Alaska Daylight Time

  • Pacific Daylight Time

  • Arizona Mountain Standard Time

  • Mountain Daylight Time

  • Central Daylight Time

  • Eastern Daylight Time

  • Puerto Rican Atlantic Standard Time

  • Coordinated Universal Time (UTC)

What is the most accurate time clock?

If you look up the atomic clock online via time.gov on your computer, laptop, tablet, smart phone or any electronic device that connects to the internet, the site will tell you how much your clock is off by. An Oct. 9 online check showed the computer laptop in which this story was written on was off by "+0.030" seconds from Coordinated Universal Time or UTC. A secondary check on an Apple iPhone 8+ said, "Your (device's) clock is off by: +0.006" seconds. Because the site is in real time, refreshing the atomic clock site will generate different results for how off your device is from UTC. It will always be off by mere seconds.

What's the status of the Sunshine Protection Act and ending daylight saving time permanently?

Where does iPhone get its time from?

One reason iPhone uses location is to set the time, but if you have the location turned off, the iPhone will still adjust time automatically, pending you selected the option "set automatically" along with your time zone under "date and time" settings. A note under the date and time settings states: "Automatic time zone accuracy is improved when location services is turned on."

When daylight saving time occurs, your iPhone will automatically "fall back" at 2 a.m. ET Sunday, Nov. 5, 2023, if the "set automatically" option was selected.

Where does Android get its time from?

Smartphones get the time from their cell phone network (T-mobile, Verizon, for example) and/or from Global Positioning System. Like iPhone, Android users can opt to manually set their time, so when daylight saving time happens, the clock on the Android device would have to be manually set. Otherwise, if the Android device has "set automatically" for "date and time" under the privacy settings, there will be no need to adjust the clock for daylight saving time.

How does Alexa know the time? Will Alexa automatically 'fall back' or 'spring forward' when it's daylight saving time?

An Amazon device with the AI assistant Alexa such as Amazon Echo or Amazon Dot will connect to the internet, and if "automatic time zone" was selected, Alexa will automatically update for daylight saving time. Manually setting your time zone on Alexa is an option. That means you would have to set your Alexa clock back by one hour in the fall or forward one hour in the spring.

Will my Fitbit or Garmin automatically change for daylight saving time?

Fitbit, Garmin and other fitness trackers use GPS and location services to tell time. When you purchase a wearable fitness tracker, it usually has an app that records your progress, uses your location and stores data. The fitness tracker app on your phone is connected to the clock on your phone, so the wearable fitness tracker's clock will update when the phone updates its time. This includes daylight saving time in the fall or spring, pending the "set automatically" open is selected under "date and time" privacy settings.

Sangalang is a lead digital producer for USA TODAY Network-Florida. Follow her on Twitter or Instagram at @byjensangalang. Support local journalism. Consider subscribing to a Florida newspaper.

This article originally appeared on Florida Today: 2023 daylight saving: Where our phones, tablets, laptops get the time