Daylight Saving Time Returns: How the Time Change Can Disrupt Your Health

On Sunday, March 8, most of the United States — including California — will once again “spring forward,” moving clocks ahead one hour at 2 a.m. to mark the start of daylight saving time (DST).

The shift brings longer daylight in the evenings, but it also means darker mornings and the loss of one hour of sleep — a change that may feel minor but can have real effects on your health and daily functioning.

Dr. Alexander Cho, a Sleep Medicine physician with Kaiser Permanente Southern California, warned that even a one‑hour disruption can throw off your internal clock, leaving many people feeling sluggish, unfocused and irritable in the days that follow.

According to Dr. Cho, research has linked the transition into DST with several short‑term health and safety concerns:

1. Disrupted Sleep Patterns

The sudden one‑hour shift can interfere with your circadian rhythm, making it harder to fall asleep or wake up on time. Many people experience grogginess, reduced concentration and slower reaction times.

2. Increased Cardiovascular Risks

Studies have found a temporary rise in heart attacks and strokes in the days immediately following the switch to DST. The stress of sleep loss and circadian misalignment may contribute to inflammation and cardiovascular strain.

3. Higher Accident Rates

Fatigue and reduced alertness can lead to more traffic collisions. Research shows a roughly 6% increase in fatal car accidents in the days after the spring time change.

4. Impact on Mental Health

DST can worsen symptoms of depression and anxiety, particularly for those already sensitive to sleep disruptions. Mood changes and irritability are also common.

5. Reduced Performance and Productivity

The adjustment period often brings general fatigue, slower cognitive processing, and decreased productivity at work or school.

“Losing even one hour of sleep can leave many people feeling fatigued,” said Dr. Cho. “This can affect your ability to perform tasks safely and effectively. Children may struggle even more, experiencing difficulty in school or changes in behavior.”

How to Prepare Your Body for the Time Change

To help ease the transition, Dr. Cho recommends taking proactive steps in the days leading up to the switch:

1. Shift Your Sleep Gradually

Go to bed 10–15 minutes earlier each night for several days before DST begins. This slow adjustment helps your body adapt more naturally.

2. Keep a Consistent Sleep Schedule

Wake up and go to bed at the same time every day — weekends included. Consistency reinforces your internal clock.

3. Get Morning Sunlight

Exposure to natural light early in the day helps reset your circadian rhythm and makes waking up easier.

4. Reduce Evening Light

Limit screen time and bright indoor lighting before bed. Dimmer light signals your body that it’s time to wind down.

5. Create a Sleep-Friendly Environment

Keep your bedroom cool, dark, and quiet. Blackout curtains, white noise machines, or eye masks can help improve sleep quality.

6. Avoid Stimulants Late in the Day

Caffeine and alcohol can interfere with falling asleep and staying asleep. Try to limit them in the afternoon and evening.

7. Give Yourself Time

Your body may need a few days to fully adjust — and that’s normal.

“There’s little doubt that losing an hour of sleep will be difficult for many at first,” Dr. Cho said. “But with the right mindset and healthy habits, you can minimize the impact.”

Looking Ahead

Daylight saving time will remain in effect until Nov. 2, when clocks “fall back” one hour and the nation returns to standard time.

For more guidance on improving your sleep year‑round, Kaiser Permanente offers additional resources and expert advice.