One minute after 1:59 AM this coming Sunday will be 3:00 AM. In most of the United States, it’s time once again to spring forward for Daylight Saving Time. Setting the clocks forward in the spring and back again in the fall goes back to 1966 in this country; since 2007 it has covered the period from the second Sunday in March to the first Sunday in November. This year, that means March 10 to November 3. The intent is to allow people who live their lives according to the clock—which is everyone, to some degree—to have an extra hour of sunlight during the main part of the day, cutting down on energy usage and avoiding traffic accidents by shifting the bulk of commuting to daylight hours.
Unfortunately, however, not all of the effects are beneficial. While traffic accidents may be reduced, researchers in Michigan say heart attacks increase; nearly twice as many heart attacks as the Sunday average occur the day after the spring shift. Another study found a ten percent increase in heart attack risk for the Monday and Tuesday immediately after moving the clocks ahead, and a corresponding decrease after moving them back in the fall. Experts suggest this may be directly related to losing an hour of sleep and the sudden schedule change.
Indeed, research shows that the time shift affects the body as a whole and several systems within it. The circadian rhythm, or body clock, is responsible for the body’s sense of what time it is. It governs such scheduled things as when we get hungry or tired. When we lose an hour, particularly what would have been an hour of sleep, the circadian clock requires recalibration.
The immune system also operates on a clock, and also requires sleep to reach its maximum potential, so the shortened night has other heath effects as well. Studies have shown that the immune response after a clock change is significantly altered. These effects can be lessened by spreading the load. By waking up half an hour early on Saturday and Sunday, you can minimize the disruption come Monday. Getting some morning sun will also help. The body adjusts quickly, so the effects don’t last beyond a week or so for most people in any event.