Today, clocks throughout the United States jump forward an hour to mark the beginning of Daylight Saving Time. The economic and energy benefits of DST have been hotly debated for nearly a century, but does it pose a health risk?

All our American readers (except those in Hawaii, Arizona, and various territories) skipped the hour between 2 and 3 A.M. this morning, creating the much dreaded 23 hour day, which somehow the promise of a 25 hour day in November never quite makes up for. The practice was first instituted in the United States back in 1918 to help the war effort, as adding more daylight to the afternoon was thought to conserve fuel and improve efficiency.


The practice was unpopular, and it was abolished shortly after the war. President Franklin Roosevelt restored the practice in 1942 as a year-round practice known as "War Time", and this lasted until September 1945. By that time, the concept of Daylight Saving Time had caught on, and it became national policy by the mid-sixties.

The actual benefits of Daylight Saving Time remain controversial. People's livelihoods can be dramatically affected by DST, both positively and negatively - retail and sports events both benefit from extra daylight, while farming and forms of evening entertainment that need night to help set the mood are more adversely affected, not to mention things that rely on precise synchronized timekeeping, which can include everything from business meetings to travel and medical devices. The impact of DST on energy consumption is very difficult to figure out based on the available data, which tends to be either woefully incomplete or entirely contradictory.

But does DST actually affect people's health? Can losing one hour in March and gaining one back in November really matter to a person's general wellness? According to Yale researcher Dr. Xiaoyong Yang, the answer is actually yes, under certain circumstances:

"Most people don't have much of a problem - they can adjust their body clock quickly. Eventually, after a couple of days, they already can adapt to the new schedule. But for some groups of people - people who have depression or a heart problem - there's some research that suggests that [they] have a higher risk of suicide and heart attack."


There's some evidence to back up that assertion. A 2008 Australian study found that men are more likely to commit suicide in the first few weeks after Daylight Saving Time begins than any other time in the year, and in the same year Swedish researchers found that serious heart attacks jump 6% to 10% during the first three workdays after DST. It's a subtle effect, but even this slight disruption to people's normal body clocks can have serious effects on those who are already dealing with serious medical conditions.

Dr. Yang suspects the shifts in biological rhythms brought on by DST can actually trigger inflammatory or metabolic reactions in the body's cells. For most people, these events are of little consequence, but individuals with depression or serious heart problems are at more of a risk.

This might not be enough to simply do away with Daylight Saving Time, but it's certainly a reminder of just how finely-tuned our biological rhythms are and how important a good night's sleep really can be. Now, if you'll excuse me, I'm going to completely disregard that lesson and stay up until 4:00 in the morning...or is it 3:00?


Via Time. Image via National Geographic.