When the clock changes and what it means for your routine

In the United States, most states change their clocks twice a year as part of Daylight Saving Time. In 2024, clocks spring forward one hour on the second Sunday in March, and fall back one hour on the first Sunday in November. When you spring forward, you lose an hour of sleep that night. When you fall back, you gain an hour.

The change happens at 2:00 a.m. local time. If you are awake, your clock jumps to 3:00 a.m. in spring, or drops back to 1:00 a.m. in fall. Most people sleep through the change, but it still affects their body clock and their schedule the next day.

Not every state observes Daylight Saving Time. Hawaii and most of Arizona stay on standard time year-round. Some U.S. territories like Puerto Rico and Guam also do not change their clocks. If you live in one of these places, the change does not affect you.

Key Takeaways

  • Clocks spring forward one hour on the second Sunday in March and fall back one hour on the first Sunday in November in most U.S. states.
  • The change happens at 2:00 a.m., so most people sleep through it, but the time shift still disrupts sleep patterns and daily routines.
  • Hawaii, most of Arizona, and several U.S. territories do not observe Daylight Saving Time and keep the same time year-round.
  • Springing forward means losing an hour of sleep and can make the next day feel harder; falling back gives you an extra hour but can confuse your body's natural rhythm.

How the spring forward change affects your sleep and energy

When clocks spring forward in March, you lose an hour of sleep. If you normally sleep from 11:00 p.m. to 7:00 a.m., that night you will actually sleep only seven hours because the clock jumps from 1:59 a.m. to 3:00 a.m. Your body does not know the clock changed—it only knows you woke up an hour earlier than usual.

The lost hour hits hardest on Monday and Tuesday after the change. You may feel more tired, have trouble concentrating, or feel irritable. Some people report headaches or trouble falling asleep the night of the change. These effects usually fade within a few days as your body adjusts to the new schedule.

To ease the transition, go to bed 15 to 30 minutes earlier for a few nights before the change. Get sunlight early in the morning on the day after the change—this helps reset your internal clock faster. Avoid caffeine after 2:00 p.m. for the first few days.

How the fall back change affects your sleep and schedule

When clocks fall back in November, you gain an extra hour of sleep. The clock goes from 1:59 a.m. back to 1:00 a.m., so if you sleep through the change, you actually sleep nine hours instead of eight. This sounds like a gift, but the extra hour can confuse your body's natural rhythm.

Some people find it harder to fall asleep at their normal bedtime because their body is not yet tired. Others wake up earlier than usual because their internal clock has not adjusted. The confusion usually lasts three to five days. Unlike the spring change, falling back does not cause the same sharp energy dip, but it can leave you feeling out of sync with your schedule.

To adjust smoothly, keep your bedtime and wake time the same for the first few days, even though the clock time has changed. This trains your body to stick to a routine rather than chasing the clock. Dim the lights in the evening to signal your body that sleep is coming.

What to do with devices and appliances when the clock changes

Most smartphones, computers, and tablets change automatically if you have automatic time zone updates turned on. You do not need to do anything—the change happens overnight. However, some older devices, car clocks, and appliances with built-in clocks may not update on their own.

Check your car's clock, kitchen appliances, wall clocks, and any smart home devices that display time. Some smart speakers and thermostats update automatically through Wi-Fi; others require manual adjustment. Microwave clocks, oven clocks, and alarm clocks almost always need to be changed by hand. Set a reminder on your phone the night before the change so you remember to update them the next morning.

If you have a medical device that tracks time—such as a glucose monitor or medication reminder—check the manufacturer's instructions. Some devices adjust automatically; others need manual updates. Call your doctor or the device maker if you are unsure.

How the time change affects work, school, and appointments

The time change can shift when sunrise and sunset happen, which affects your commute and outdoor activities. In spring, the sun rises later, so your morning commute may be darker. In fall, the sun sets earlier, so your evening is darker sooner. This change is gradual over the weeks after the clock change, not when ready.

Work and school schedules stay the same—your 9:00 a.m. meeting is still at 9:00 a.m. on the clock. However, the actual time of day relative to sunrise and sunset shifts. If you have outdoor activities or exercise routines tied to daylight, you may need to adjust when you do them.

Appointments scheduled around the time of the change can cause confusion. If you have an appointment at 2:30 a.m. on the night of the spring change (which is rare), it may not exist—the clock jumps from 1:59 a.m. to 3:00 a.m. For fall, an appointment at 1:30 a.m. happens twice. In practice, this almost never matters because appointments are scheduled during waking hours. Just double-check any unusual early-morning or late-night appointments scheduled for the night of the change.

States and territories that do not change their clocks

Hawaii has not observed Daylight Saving Time since 1967. Most of Arizona does not change clocks either—only the Navajo Nation within Arizona observes Daylight Saving Time. These places stay on Hawaii-Aleutian Standard Time or Mountain Standard Time year-round.

U.S. territories that do not change clocks include Puerto Rico, the U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands. If you live in or travel to these places, you do not need to adjust your clock or your routine.

Some states have proposed staying on one time year-round instead of changing twice a year, but as of now, only Hawaii and Arizona have made that choice permanent. If you move to a different state, check whether it observes Daylight Saving Time, because the change date is the same nationwide for states that do observe it.

Frequently Asked Questions

Why do we change the clocks if it causes sleep problems?

Daylight Saving Time was created to align waking hours with daylight and was intended to save energy. The energy savings are small or nonexistent in modern times, but the practice continues because changing the law requires federal action. Some states have tried to opt out or stay on one time year-round, but federal law currently requires states to observe standard time if they do not observe Daylight Saving Time.

Does the time change affect children and pets?

Children and pets rely on routine and sunlight cues to regulate sleep, so the time change can disrupt their schedules. Children may be fussy or have trouble sleeping for a few days. Pets may want to eat or go outside at different times. Keep their routines as consistent as possible by feeding and exercising them at the same clock time for the first week after the change.

What if I forget to change my clock?

If you forget to change a wall clock or appliance clock, you will be an hour off until you notice and fix it. For work and appointments, your phone and computer will likely update automatically, so you should not miss anything. Just update any manual clocks when you realize the change happened.

Does the time change happen on the same day everywhere in the world?

No. The United States changes clocks on the second Sunday in March and the first Sunday in November. Europe changes on the last Sunday of March and the last Sunday of October—different dates. Many countries do not observe Daylight Saving Time at all. If you work with people in other countries or travel internationally, check their local time change dates.

Can I adjust my sleep schedule before the time change to make it easier?

Yes. Before spring forward, go to bed 15 to 30 minutes earlier for a few nights to build up sleep reserves. Before fall back, you can shift your bedtime slightly later a few nights before, though the effect is less dramatic. Getting morning sunlight and avoiding caffeine in the afternoon also helps your body adjust faster after the change.