Daylight Saving Time Destroys Your Circadian Rhythm—Here's How to Recover

It's just one hour. How bad could it be?

Turns out, pretty terrible. The Monday after Daylight Saving Time (DST) sees a 24% spike in heart attacks, a 6% increase in fatal car accidents, and a measurable drop in productivity that costs the economy billions.

All from moving the clock forward or back by 60 minutes.

The problem isn't the hour itself—it's that your circadian rhythm doesn't care what the clock says. Your internal biological clock needs 3-7 days to adjust, and during that transition period, your body is in a state of misalignment called "social jet lag."

Here's the science on why DST wreaks havoc on your sleep and health, how long recovery actually takes, and the strategies to minimize the damage.

Why One Hour Feels Like Jet Lag

Your circadian rhythm is controlled by a master clock in your brain (the suprachiasmatic nucleus, or SCN). This clock regulates:

• When you feel sleepy or alert
• Body temperature fluctuations
• Hormone release (melatonin, cortisol, growth hormone)
• Digestive processes
• Cognitive performance

This clock is set primarily by light exposure, but it takes several days to shift even by an hour. When the clock says 7 AM but your body thinks it's 6 AM, everything is out of sync.

Social Jet Lag: Living in Two Time Zones

Social jet lag is the misalignment between your biological clock and social obligations (work, school, etc.). During DST transitions:

• Spring forward (losing an hour): Your body wants to sleep until 8 AM, but the clock says 9 AM and you need to be at work
• Fall back (gaining an hour): Your body wants to wake at 6 AM, but the clock says 5 AM and it's still dark

This misalignment creates sleep deprivation, mood disruption, and cognitive impairment—the same symptoms as flying across time zones.

The Health Consequences of DST

The research on DST's impact is extensive and alarming. Here's what happens during the transition period:

1. Cardiovascular Events Spike

The Monday after spring DST sees a significant increase in heart attacks:

• +24% increase in heart attacks on the Monday after "springing forward"
• -21% decrease on the Tuesday after "falling back" (gaining sleep is protective)

Why? Sleep deprivation increases cortisol (stress hormone), raises blood pressure, and increases inflammation—all risk factors for cardiovascular events.

2. Car Accidents Increase

The Monday after spring DST shows:

• +6% increase in fatal car accidents
• Higher rates of accidents during morning commute (7-9 AM)
• Reaction time impairment equivalent to driving with blood alcohol of 0.05%

Losing one hour of sleep increases crash risk by 33% compared to getting 7 hours.

3. Workplace Injuries and Productivity Loss

Studies show measurable impacts on workplace performance:

• +5.7% increase in workplace injuries during the week after spring DST
• 68% more work days lost to injuries during this period
• 20% productivity drop in the first 2-3 days after transition

4. Mental Health and Mood Disruption

Circadian misalignment affects mental health:

• Increased depressive episodes following DST transitions
• Higher rates of suicide in the weeks following spring DST
• Irritability, anxiety, and reduced stress tolerance

Spring Forward vs. Fall Back: Which Is Worse?

Verdict: Spring forward (losing sleep) is far worse than fall back (gaining sleep). Gaining sleep has mild protective effects, while losing sleep amplifies health risks.

Why Your Body Takes 3-7 Days to Adjust

Your circadian rhythm shifts at a rate of about 1 hour per day under ideal conditions. But DST transitions aren't ideal:

The Circadian Shift Rate

• Light exposure timing: If you don't get bright light at the right time, adjustment is slower
• Sleep debt: If you're already sleep-deprived, recovery takes longer
• Age: Older adults (60+) take longer to adjust (up to 10 days)
• Chronotype: Night owls struggle more with spring forward; early birds struggle more with fall back

The Sleep Debt Compounding Effect

Most people are already running a sleep deficit (getting 6-7 hours instead of 7-9). DST compounds this:

• Night 1 (Sunday): Lose 1 hour = net -1 hour sleep debt
• Night 2-5 (Monday-Thursday): Still adjusting, sleeping poorly, accumulating 15-30 min additional debt per night
• By Friday: Total accumulated sleep debt of 2-3 hours

By the end of the first week, you're not just dealing with a 1-hour shift—you're dealing with significant cumulative sleep deprivation.

How to Recover Faster: The 3-Day Pre-Adjustment Strategy

The best way to handle DST is to not let it surprise your body. Here's how to minimize the damage:

3 Days Before: Start Gradual Adjustment

For Spring Forward (losing an hour):

• Day -3: Go to bed 15 minutes earlier, wake 15 minutes earlier
• Day -2: Go to bed 30 minutes earlier, wake 30 minutes earlier
• Day -1: Go to bed 45 minutes earlier, wake 45 minutes earlier
• DST Sunday: You're now only adjusting by 15 minutes instead of 60

For Fall Back (gaining an hour):

• Less critical, but still helpful to gradually shift 15 min/day
• Focus on keeping wake time consistent to avoid oversleeping

Light Exposure: The Most Powerful Tool

Light is the strongest circadian time cue. Use it strategically:

Spring Forward:

• Get bright light exposure immediately upon waking (even before DST hits)
• Go outside within 30 minutes of waking—10-15 minutes of sunlight
• Use a light box (10,000 lux) if sunrise is too early

Fall Back:

• Get light exposure later in the morning to delay your clock
• Avoid bright light immediately upon waking
• Exercise in afternoon light to help shift rhythm later

Keep Wake Time Consistent

This is counterintuitive but critical: Keep your wake time consistent, even if bedtime is hard to shift.

Wake time is more powerful than bedtime for setting your circadian rhythm. Even if you go to bed later than planned, waking at the new time helps your body adjust faster.

Avoid Common Mistakes

Don't do these:

• ❌ Sleep in on Sunday to "catch up" (makes adjustment harder)
• ❌ Compensate with extra caffeine (delays adjustment, disrupts sleep)
• ❌ Take long naps (reduces sleep pressure for nighttime)
• ❌ Use alcohol to fall asleep (worsens sleep quality)

Do these instead:

• ✅ Short 15-20 min power nap before 2 PM if desperate
• ✅ Cut caffeine by 12 PM (earlier than usual)
• ✅ Exercise in morning light (reinforces circadian timing)
• ✅ Keep bedroom cool and dark for better sleep quality

Special Populations: Who Struggles Most

Night Owls

If you're naturally a late chronotype, spring forward is brutal. Your body already wants to sleep later, and DST forces you to wake even earlier relative to your biology.

Strategy: Be extra aggressive with morning light exposure and consider adjusting 5 days in advance instead of 3.

Parents of Young Children

Kids take longer to adjust (sometimes 2-3 weeks for very young children). Toddlers don't understand why "bedtime" is suddenly different.

Strategy: Shift kids' schedules by 10-15 minutes per day starting a week before DST.

Older Adults (60+)

Circadian rhythms become less flexible with age, and sleep is already more fragmented. DST transitions can take 7-10 days or more.

Strategy: Extra caution with driving during adjustment period. Consider taking the Monday after spring DST off if possible.

Sources & Further Reading

1. Janszky I, Ljung R. Shifts to and from Daylight Saving Time and incidence of myocardial infarction. New England Journal of Medicine. 2008;359:1966-1968. View study
2. Barnes CM, Wagner DT. Changing to daylight saving time cuts into sleep and increases workplace injuries. Journal of Applied Psychology. 2009;94(5):1305-1317.
3. Fritz J, et al. A chronobiological evaluation of the acute effects of daylight saving time on traffic accident risk. Current Biology. 2020;30(4):729-735.
4. Roenneberg T, Allebrandt KV, Merrow M, Vetter C. Social jetlag and obesity. Current Biology. 2012;22(10):939-943.
5. Kantermann T, Juda M, Merrow M, Roenneberg T. The human circadian clock's seasonal adjustment is disrupted by daylight saving time. Current Biology. 2007;17(22):1996-2000.

Last updated: January 2026