8 ways that daylight saving time affects us

• Night owls tend to have more trouble with DST than early birds%2C study finds
• Another study finds a spike in heart attacks during first week of DST
• DST first implemented during World War I to save fuel

DES MOINES, Iowa -- Worried you'll feel a little groggy from missing an hour of sleep Saturday night? You're not alone. Daylight saving time affects us all in more ways than you might think. Here are eight of them:

1. For starters, it's "daylight saving time" -- without an "s" on the end of "saving." Now you can correct all your friends.

2. President George W. Bush signed the Energy Policy Act into law in 2005, which extended the length of DST by four weeks. It now begins at 2 a.m. on the second Sunday in March and ends on the first Sunday in November -- except in Hawaii and Arizona, where they observe standard time year-round. With all that sunshine, they probably don't even care what time it is. (Parts of Indiana, by the way, resisted DST until 2006.)

3. The time switch has mixed effects on people's health. Night owls tend to have more trouble than early birds, according to a Finnish study in 2008, but everyone's sleep patterns can be disrupted by the transition into or out of DST. That may be especially true in Kazakhstan, where the government did away with DST in 2005 after calculating that 51.6 percent of Kazakhs responded badly to the time change. (Who knew?)

4. There is a spike in heart attacks during the first week of DST, as well as a slight drop in attacks during the first week after DST ends, according to another 2008 study, published in The New England Journal of Medicine. Researchers tagged the "spring forward" results to sleep deprivation, which affects heart health. Conversely, the extra hour of "fall back" sleep promotes general well-being.

5. No surprise here, but people are safer drivers during daylight hours. Information from U.S. News Health indicates that observing DST year-round could prevent 195 motor-vehicle deaths and 171 pedestrian fatalities per year.

6. Credit (or blame) for DST rests with Benjamin Franklin, who published "An Economical Project for Diminishing the Cost of Light" in a 1784 journal after he noticed that people burned candles at night but slept past dawn. But he never saw his plan put into action. The United States first implemented it during World War I as a way to conserve fuel.

7. Recent data suggest that Franklin's energy-savings theory was only part of the equation. The average DST observer (aka all Americans except those in Hawaii and Arizona) uses 1 percent less energy for lighting but 2 percent to 3 percent more for heating and air-conditioning.

8. Many fire departments encourage homeowners to change the batteries in their smoke detectors when they change their clocks for DST. It's a convenient reminder: Have you changed yours?