Spring Ahead = Sleep Reset: What Daylight Saving Time Does to Your Body (and How to Handle It)
By Marina Tonial, MPH, CHES®
When we “spring ahead,” we lose just one hour of sleep — but your body doesn’t experience it as small. That single hour shifts your internal clock, also called your circadian rhythm, which regulates sleep, mood, focus, metabolism, and even heart function.
For many people, the week after the time change feels like jet lag without the travel. And for kids, teens, and early-morning workers, the effects can last even longer.
Why One Hour Matters
Your brain runs on light signals. Morning sunlight tells your body to wake up and release alertness hormones. Darkness triggers melatonin — the sleep hormone. When the clock suddenly moves forward, your brain is still operating on the old schedule.
In other words: your alarm goes off before your body is ready.
Effects on Mood and Mental Health
Research consistently shows a temporary increase in irritability, low mood, anxiety symptoms, difficulty concentrating, and mistakes at work and school during the days following the time change.
This happens because sleep loss affects emotional regulation — the part of the brain that helps you manage stress. Even mild sleep deprivation reduces patience, motivation, and decision-making ability.
For people already managing depression, ADHD, or anxiety, symptoms may briefly feel more intense during the adjustment week.
The good news: most people readjust within 5–7 days when they actively support their sleep schedule.
Effects on Heart Health
Some research suggests that the Monday after daylight saving time shows a small but measurable increase in heart attack and stroke risk.
Sleep loss can trigger increased blood pressure, higher inflammation, and elevated stress hormones — all of which place extra strain on the cardiovascular system. This doesn’t mean the time change is dangerous for most people, but it does underscore how deeply sleep affects physical health.
Kids, Teens, and Learning
Children and teenagers tend to feel the shift most acutely. Their brains are naturally wired to fall asleep later than adults, which means waking up an hour earlier is especially disruptive. In the days after the time change, schools often notice more behavioral issues, lower attention span, slower reaction time, and increased morning fatigue.
Put simply: their brains are still asleep during first period.
Reset Your Circadian Rhythm: A 3-Day Adjustment Plan
3 days before the change: Start shifting your bedtime 15–20 minutes earlier each night. Dim lights after 8 PM and reduce screen use late in the evening.
The morning of the change: Get outside within 30 minutes of waking up. Morning sunlight is the fastest way to reset your internal clock — more effective than caffeine at signaling your brain that it’s time to be awake.
For the first week: Eat meals at consistent times, avoid naps longer than 20 minutes, exercise earlier in the day, cut off caffeine at least 8 hours before bed, and keep your wake-up time consistent — even on weekends.
Productivity Tip: Don’t Fight the Slump
Your brain’s peak alertness shifts later for a few days after the time change. Rather than forcing early-morning productivity and getting frustrated, try temporarily adjusting your schedule: use the morning for routine tasks, midday for meetings and communication, and the afternoon for focused work.
Working with your body — not against it — improves both performance and mood.
The Bottom Line
Daylight saving time isn’t just a clock change — it’s a body change. Sleep affects mental health, learning, safety, and heart health more than most people realize.
Treat this week like recovery, not failure. Give your brain sunlight, consistency, and patience — and it will reset.
If your sleep disruption persists beyond two weeks, it may be worth speaking with your doctor.
Sources and Further Reading
- New England Journal of Medicine – “Shifts to and from Daylight Saving Time and Incidence of Myocardial Infarction” (2008) https://www.nejm.org/doi/full/10.1056/NEJMc0807104
- National Library of Medicine – “Daylight Saving Time and Acute Myocardial Infarction: A Meta-Analysis” (2019) https://pmc.ncbi.nlm.nih.gov/articles/PMC6463000/
- American Heart Association – “Here’s Your Wake-Up Call: Daylight Saving Time May Impact Your Heart Health” (2024) https://newsroom.heart.org/news/heres-your-wake-up-call-daylight-saving-time-may-impact-your-heart-health
- Harvard Health Publishing – “The Dark Side of Daylight Saving Time” (2023) https://www.health.harvard.edu/staying-healthy/the-dark-side-of-daylight-saving-time
- Johns Hopkins Bloomberg School of Public Health – “7 Things to Know About Daylight Saving Time” (2023) https://publichealth.jhu.edu/2023/7-things-to-know-about-daylight-saving-time
- National Library of Medicine – “Adverse Effects of Daylight Saving Time on Adolescents’ Sleep and Vigilance” (2015) https://pmc.ncbi.nlm.nih.gov/articles/PMC4513265/
- Mass General Brigham – “Sleep Disorders in Teens: Prep for Daylight Saving Time” https://www.massgeneralbrigham.org/en/about/newsroom/articles/daylight-savings-impact-teens-sleep-schedule
- American Academy of Sleep Medicine – “Daylight Saving Time” https://sleepeducation.org/resources/daylight-saving-time/
- Stanford Medicine – “Study Suggests Most Americans Would Be Healthier Without Daylight Saving Time” (2025) https://med.stanford.edu/news/all-news/2025/09/daylight-saving-time.html
- UT Southwestern Medical Center – “Why Daylight Saving Time May Be Bad for Your Brain and Health” https://utswmed.org/medblog/daylight-saving-time-sleep-health/
