Daylight saving time and sleep: how to adjust when the clocks change

Daylight saving time affects sleep because it moves the clock by an hour while your body clock stays where it was. The spring change, when you lose an hour, is the harder one: studies link the days after it to shorter sleep, more fatal car crashes and a small rise in heart attacks. The fall change is gentler, but it can still throw off your wake-ups for a few days. Adjusting gradually, using morning light and protecting the sleep you do get all help.

When do the clocks change in the US?

US daylight saving time ended at 2 a.m. local time on Sunday, November 1, 2026, when clocks fell back an hour. According to NIST, current federal rules start daylight saving time at 2 a.m. on the second Sunday of March and end it at 2 a.m. on the first Sunday of November. That puts the next spring change on Sunday, March 14, 2027, unless the law changes before then.

Not everyone switches. NIST lists Hawaii and Arizona (apart from the Navajo Indian Reservation, which does observe it) as places that don't observe daylight saving time, along with several US territories.

Why do clock changes affect sleep?

Clock changes affect sleep because your internal clock is set mainly by light, not by the time on your phone. The American Academy of Sleep Medicine (AASM) calls light the most powerful outside cue for your circadian rhythm. Daylight saving time gives you darker mornings and brighter evenings, and its 2020 position statement explains that both push the body clock later.

So in spring, your alarm goes off an hour earlier by your body's reckoning, while bright evenings make it harder to feel sleepy at the new bedtime. The AASM says that, with work and school still starting early, this leads to sleep loss and sleep debt on top of the misalignment. In fall the shift runs the other way. You get an hour back, but your body may wake before the alarm and feel ready for bed earlier than usual.

What does the research show about the spring change?

The research on the spring change points mostly in one direction: the days after "springing forward" carry measurable risks.

The strongest signal comes from road safety. A 2020 study in Current Biology looked at 732,835 fatal car crashes recorded across the US from 1996 to 2017. The spring change raised fatal crash risk by 6%, with the increase more pronounced in the morning and in places further west within a time zone. The rise faded over the following week, and the fall change back to standard time had no effect on fatal crash risk. The authors suggest preventable sleep loss and circadian misalignment may underlie the increase.

Heart health shows a smaller effect. A 2019 meta-analysis in the Journal of Clinical Medicine pooled seven studies with more than 115,000 people. Heart attack risk rose modestly but significantly after the spring shift (odds ratio 1.05), while the week after the autumn change looked the same as control periods. The authors called for more studies that fully adjust for confounders.

Sleep itself drops, at least at first. A 2025 analysis of UK Biobank accelerometer data from 11,780 adults aged 43 to 78 found that mean sleep on the Sunday of the spring change was 65 minutes shorter than the Sunday before. On the autumn change Sunday, people slept about 33 minutes longer. There was some sign of catch-up sleep during the following week. These are observational studies, so they show associations rather than proof of cause, but they line up with what the AASM describes.

What does the AASM recommend?

The AASM's position is that the US should end seasonal clock changes and adopt permanent standard time. Its 2020 statement says the shift into daylight saving time "incurs significant public health and safety risks," including heart events, mood disorders and car crashes. The 2024 update repeats the call for permanent standard time, which it says aligns best with human circadian biology.

That's a policy position, and it doesn't change what happens in your bedroom next March. Until the law changes, the useful question is how to get through each switch with as little lost sleep as possible.

How is the fall change different?

The fall change is usually easier because you gain an hour instead of losing one. The UK Biobank data showed more sleep, not less, on the autumn change Sunday, and the US crash study found no rise in fatal crashes after it.

It isn't always smooth, though. The AASM notes that transitions both into and out of daylight saving time have been linked to sleep disruption and mood disturbances. Sleep Foundation adds that some people have trouble adjusting to the new wake-up time. If you're waking at 5 a.m. this week and fading by 9 p.m., that's your body clock still running an hour ahead. For most people these effects fade over a few days to a few weeks.

How do you adjust to the clock change gradually?

You adjust to a clock change gradually by moving your schedule in small steps and letting light do the heavy lifting. Here's a plan that works for either direction.

Shift in small steps before spring

Sleep Foundation suggests gradually adjusting your schedule: for two to three days before the spring change, wake up 15 to 20 minutes earlier than usual. By Sunday, the jump is smaller.

Keep your wake time steady after the change

Pick your wake time on the new clock and stick with it every day, weekends included. Sleep Foundation lists a consistent sleep routine as one of the main ways to adapt. A steady wake time anchors your body clock more reliably than trying to force an early bedtime.

Get morning light

Go outside early in the day. Sleep Foundation says natural light helps reorient your circadian rhythm and can ease morning tiredness. After the fall change, mornings are brighter, so a walk or coffee outside soon after waking helps you settle into the new schedule. After the spring change, mornings are darker, which makes deliberate morning light even more useful.

Go easy on evening light

Because evening light pushes the body clock later, dim the lights and put screens down a little earlier in the week after the spring change. Our guide to screens before bed has practical ideas.

Watch caffeine, alcohol and naps

Sleep Foundation recommends avoiding alcohol before bed, being mindful of caffeine later in the day, and keeping naps to 20 minutes or less. Each of these protects the sleep you get on nights when it's already short. Our napping tips have more on keeping naps short.

Plan around the riskiest days

Given the crash data, be careful with early drives on the Monday after the spring change. If you feel drowsy, don't drive.

Can easier breathing help during a clock change week?

Easier breathing won't reset your body clock, but it can protect the sleep you have when the clock change has already cut it short. If a blocked nose or snoring wakes you or your partner, a week with less sleep than usual is a bad time to lose more of it.

The NHS lists nasal dilators or strips for snoring caused by blocked or narrow airways in the nose, and sleeping on your side for snoring in general. For people whose mouth falls open at night, small studies on mouth taping are encouraging. In a 2022 study in Healthcare of 20 mouth breathers with mild sleep apnea, a home sleep test taken one week after a baseline test, on a night with the mouth taped, showed the median snoring index and apnea-hypopnea index each fell by about half. That's one small study without a control group, so it's a promising early result, not proof.

If both your nose and mouth are part of the problem, a combined routine like the Titan Sleep System covers both at once. Our guide to using mouth tape and nasal strips together explains how the two fit.

We don't recommend mouth tape for children. Mouth tape is only for adults who can breathe comfortably through the nose; try our nose test first.

When should you see a doctor?

See a doctor if you're still exhausted weeks after a clock change, because that points to something more than a one-hour shift. Ongoing tiredness can come from too little sleep, insomnia or a sleep disorder. Our guide to how much sleep adults need is a good starting check.

The NHS says to see a GP if you feel sleepy during the day, your breathing stops and starts while you sleep, or you make gasping or choking noises. Those are possible signs of sleep apnea, which can be serious if not treated, and they're worth checking before you try mouth tape. Read more in our sleep apnea warning signs guide. If your nose is blocked most nights, get it looked at, and if you're pregnant, ask your clinician before starting any new sleep product.

Our pick (paid partner): Titan Sleep System

For a clock change week, or any stretch when sleep is in short supply, our pick for nighttime breathing is the Titan Sleep System. We haven't tested or ranked sleep products ourselves; this is our recommendation, based on how Titan describes the system. It won't fix circadian misalignment, but it's a simple way to support nose breathing while your schedule settles.

Titan describes the Sleep System as TitanAir Nasal Strips and Titan Bamboo Silk Mouth Tape together as one nightly system. Titan says the strips are drug-free external nasal dilators with flexible spring-loaded bands, placed just above the flare of the nostrils on the soft part of the nose, not the bony bridge. The tape is a bamboo silk strip that Titan describes as soft and breathable, worn horizontally across the lips.

Titan says every batch is third-party tested and certified PFAS-free, and it offers a 30-night guarantee. If you only need one half, Titan also sells TitanAir Nasal Strips on their own.

Read next

• Sleep hygiene: the habits with the best evidence
• Why do I wake up at 3am?
• Titan Sleep System guide

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.