Why One Hour Matters So Much

Gain an Hour, Gain Some Risks

A host of problems and risks arises when people’s sleep cycles are thrown off. When we lose an hour in the spring, drowsiness and stress increase. And even though we get extra snooze time in the autumn, the shift back to standard time creates more dark hours than light, which makes us feel more tired and leads to higher rates of seasonal affective disorder (SAD).

SAD shares many of its symptoms with depression, so even if people aren’t clinically depressed, being affected by the lack of light makes them start to feel that way. Messing in any way with the body’s chronobiological processes (the mechanisms controlling its circadian rhythms) encourages the effect. A 2008 study published in Sleep and Biological Rhythms looked at suicide rates in Australia from 1971 to 2001. The rates tended to increase at the start and end of daylight saving time, which could mean that even small changes can have major emotional consequences for some people.

The end of daylight saving also raises the risk of vehicle-related incidents. A 2003 study conducted jointly at Stanford University and John Hopkins University analyzed over twenty years’ worth of data and found that a large number of accidents occur on Sundays marking the end of daylight saving time. And the danger isn’t just for motorists—a Carnegie Mellon University study in 2007 showed a whopping 186 percent increase in pedestrian fatalities in November after the fall-back to standard time. Because rates lowered in December, researchers suggested it had something to do with people’s getting used to driving and being active in the dark again.