Daylight Saving Time, the spring move of clocks forward one hour, cuts one night short and pushes the body clock later. Runners feel groggy on early runs and alert at night because morning light arrives later and evening light lasts longer. That mismatch lasts longer than one weekend. Light controls the sleep-wake cycle, so bedtime, wake time, and training feel out of sync until the body resets.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- Why early miles feel harder
- Why runners feel a small loss more
- How much sleep protects training
- How to reset in two weeks
Why early miles feel harder
Springing forward removes one hour of overnight sleep. It also shifts light from morning to evening. COROS notes this delay makes runners tired in the morning and alert at night. Light is the strongest setter of the internal clock.
Evening light tells the brain to stay awake. Missing morning light delays the signal to wake up. Iowa Sleep Center sleep physician Steven Zorn says the body needs about one to two weeks to re-establish a satisfactory rhythm, according to the Iowa Sleep Center report via MyBestRuns. That means several training days can feel off. Early alarms clash with a body that is not ready for sleep yet.
Why runners feel a small loss more
Cleveland Clinic sleep specialist Ralph Downey III says endurance athletes pay the biggest price for reduced sleep. Even small losses reduce motivation and stamina for sustained efforts like running and cycling. The link between more sleep and better performance is direct. Stanford men's basketball players who extended sleep to about 10 hours nightly ran faster sprints.
They also improved free-throw and three-point shooting about 9% and reported better mood and less fatigue. Short nights also raise injury risk. Connecticut Children's reports athletes sleeping under 8 hours nightly were 1.7 times more likely to be injured than those sleeping 8-plus hours, in Connecticut Children's guidance on athlete sleep. For runners, that turns a clock change into a training hazard.
How much sleep protects training
Most adults need at least 7 hours nightly. Elite athletes reported needing 8.3 hours to feel rested. Experts recommend athletes target 8 to 10 hours for recovery, according to CDC data shared via Nike. That target leaves little margin after the spring shift.
One short night can push a runner who already sleeps six to seven hours further below the range tied to injury and poor recovery. The wider health scare needs context. A Duke meta-analysis of 170,000 people over 10 years found no significant heart-attack increase around DST, as reported by Cape Cod Health. Acute cardiac risk from one lost hour appears small and disputed.
How to reset in two weeks
The American Academy of Sleep Medicine urges permanent standard time because it best matches sleep-wake biology. Runners still must adjust twice a year while seasonal changes continue.
COROS recommends tracking sleep for two weeks and adding about 15 minutes every few nights, detailed in the COROS guide to resetting after the time change. Use these steps to ease the shift: Move bedtime earlier in small steps rather than one jump. Morning light exposure and a consistent run time help lock the new rhythm.
- Keep the bedroom cool, dark, and quiet.
- Cut evening screen time, caffeine, and alcohol.
- Hold a steady bedtime and wake time, even on weekends.
- Add a short nap when night sleep falls short.