Summary: Shifting clocks forward for daylight saving time disrupts the body’s circadian rhythm and can cause sleep loss, increased stress, and other health consequences. Experts explain why some people are more affected and offer practical, science-based strategies to ease the transition.
Source: UT Southwestern
If you find yourself feeling unusually tired this week, that’s a common reaction. Advancing clocks by one hour for daylight saving time (at 2 a.m. on Sunday) forces the body’s internal clock to shift, temporarily disrupting sleep patterns, alertness, and overall functioning, according to Joseph Takahashi, Ph.D., a neuroscientist at UT Southwestern who studies circadian rhythms.
“Waking up an hour earlier increases physiological stress and can reduce total sleep time,” said Joseph Takahashi, Ph.D., Professor and Chair of Neuroscience at UT Southwestern’s Peter O’Donnell Jr. Brain Institute. “Misaligned circadian rhythms have been associated with elevated risks for conditions such as heart attack, depression, and certain cancers.”
Dr. Takahashi, a Howard Hughes Medical Institute Investigator noted for identifying the first mammalian circadian gene, explains how the time change interferes with biological timing and what practical steps people can take to adapt more smoothly.
Who is most affected by daylight saving time?
People vary in their chronotype—the natural tendency to wake and sleep earlier or later. “Night owls,” who prefer late bedtimes and later wake times, typically feel the shift more strongly because advancing the clock forces them to rise earlier than their internal rhythm prefers. “Larks,” or early risers, generally experience less disruption. Recognizing your chronotype helps set realistic expectations about how quickly you’ll adjust.
Why does the clock change increase heart attack risk?
Cardiovascular events show a pronounced morning peak, and even modest sleep loss or circadian misalignment can raise physiological stress markers. Waking earlier than usual increases sleep deprivation and stress, which may contribute to a short-term rise in heart attack risk for vulnerable individuals.
Practical steps to reduce the impact of daylight saving time
You can reduce the effects of the time change by focusing on sleep consistency and light exposure, which are the strongest cues for the circadian system. Below are evidence-based, practical tips to help your body reset more quickly and protect your health:
- Keep a consistent sleep schedule: Go to bed and wake up at the same times each day, even on weekends, to stabilize your internal clock.
- Prioritize morning light: Exposure to bright light soon after waking—preferably outdoors—signals your brain that it is daytime and helps shift your rhythm earlier. Aim for at least 20–30 minutes of daylight when possible.
- Adjust gradually if possible: If you know the change is coming, try going to bed 15–30 minutes earlier several nights before the switch to make the transition smoother.
- Limit late-night light exposure: Reduce screen time and bright artificial light in the hour before bedtime to allow sleep-promoting hormones to rise naturally.
- Watch stimulants and alcohol: Avoid caffeine late in the day and limit alcohol near bedtime, as both can fragment sleep.
- Use naps strategically: If you’re short on sleep, a brief nap (20–30 minutes) can restore alertness without interfering with nighttime sleep.
- Keep a restful sleep environment: Make your bedroom cool, dark, and quiet. Comfortable bedding and a relaxing pre-sleep routine support better sleep quality.
- Time exercise appropriately: Regular physical activity helps regulate sleep, but intense workouts close to bedtime may make it harder to fall asleep—try to finish vigorous exercise several hours before bed.
If you have existing health conditions—especially cardiovascular disease, mood disorders, or significant sleep disorders—discuss the time change with your healthcare provider so you can take individualized precautions. For most people, these behavioral strategies will ease the transition within a few days to a couple of weeks.
Dr. Takahashi holds the Loyd B. Sands Distinguished Chair in Neuroscience and continues to study how circadian biology influences health.
About this sleep research news
Author: Press Office
Source: UT Southwestern
Contact: Press Office – UT Southwestern
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