Daylight Savings Time Affects Heart Attack Incidence : Pure Pedantry

Reality is always more complicated than you think.

Profile

Jake Young is a MD/PhD student at Mount Sinai School of Medicine in NYC getting a PhD in Behavioral Neuroscience. He holds a BS and MS in Biological Sciences from Stanford University. If a volcano were to erupt Pompei-style in Central Park, his body would be preserved in a scoliotic posture over his lab desk. Archeaologists would later conclude that he spent most of his day training rats to perform tricks, until he went blind building electrical equipment by hand using a dissecting microscope. But, still, he died happy...because science is cool.

Pure Pedantry is a blog about science -- social sciences and otherwise -- as well as academic and scientific culture. No one can live on science alone, so I also like to dwell on pop culture, periodically explore the humanities, and indulge in other types of geeky goodness.

DISCLAIMERS: 1) Jake Young is not a licensed physician (yet). He is merely a medical student. The information published on this site is not intended for use in medical decision-making. Please seek advice from a licensed, medical professional before making any health decisions. 2) The opinions expressed are my own. They do not represent the views of SEED magazine or the educational establishments I currently attend or attended in the past.

Search

Daylight Savings Time Affects Heart Attack Incidence

Category: Obesity and Heart Disease • Sleep
Posted on: October 31, 2008 9:37 AM, by NotoriousLTP

This Sunday you are slightly less likely to have a heart attack.

Swedish researchers, publishing in the NEJM, looked at a registry of heart attacks from 1987 to 2006. They found that the incidence of heart attacks slightly increases for the three days following the Spring daylight savings time where we lose an hour. The incidence of heart attacks slightly decreased on the day after Fall daylight savings time:

We used data from the Swedish registry of acute myocardial infarction, which provides high-quality information on all acute myocardial infarctions in the country since 1987. The incidence ratios, as measures of relative risk, and exact 95% confidence intervals were calculated.
The incidence of acute myocardial infarction was significantly increased for the first 3 weekdays after the transition to daylight saving time in the spring (Figure 1A). The incidence ratio for the first week after the spring shift, calculated as the incidence for all 7 days divided by the mean of the weekly incidences 2 weeks before and 2 weeks after, was 1.051 (95% confidence interval [CI], 1.032 to 1.071). In contrast, after the transition out of daylight saving time in the autumn, only the first weekday was affected significantly (Figure 1B); the incidence ratio for the whole week was 0.985 (95% CI, 0.969 to 1.002).

The authors attribute the change to getting one less hour of sleep during the Spring and one more hour of sleep during the Fall.

While the effect sizes are super-small and I am a bit skeptical about their ideas for mechanism (changes in pro-inflammatory cytokines due to changes in circadian rhythm), this is still a funny and cool story.

Hat-tip: NPR

Share this: Facebook Twitter Stumbleupon Reddit Email + More

Find more posts in: Medicine & Health

Comments

Besides the sleep issue, could it also be stress? I forgot about daylight savings time, and relieved and relaxed at having an extra hour. If I forgot in the Spring I would be anxious and upset about losing the hour. In the Spring it's also likely to make you late for something which will increase your stress levels. Whereas, in the Fall you'll have an extra hour to prepare.

Posted by: penn | November 2, 2008 10:40 AM