These inconclusively demonstrated benefits, according to AASM, are not worth the human lives lost to daylight saving. Conversely, there may be significant health benefits, both physical and mental, to a regular time schedule.
The human circadian rhythm is the hour biological cycle that, among other things, regulates our sleep-wake cycle - although this cycle can be artificially altered, as shift workers well know. As we also know from studies on shift workers, such alterations can lead to dangerous and health-degrading sleep disorders. AASM believes that a similar effect is at play when our sleep time is abruptly shifted back an hour. And there's certainly plenty of evidence that the DST switch can have effects a lot worse than being more sleepy than usual for a few days while you adjust.
Some effects are relatively mild. Immediately after the shift to daylight saving time, people are less productive, and slack off at work more. Students have been found to perform more poorly on tests. For one thing, its primary justification no longer stands up to scrutiny. But researchers attempting to measure the effects of clock-changing on energy savings have found them pretty elusive.
Economist Matthew Kotchen, a professor at the Yale School of the Environment, discovered that after daylight saving time was implemented in Indiana, the change increased electricity consumption by 1 percent. And in regions where demand for air conditioning is greater and growing, daylight saving time is likely to increase electricity use even more. In another empirical study , scientists at the University of California, Berkeley, examined the use of energy before and after daylight saving time was adopted in parts of Australia during the Olympics.
It also generates a slew of harms. In the days following the onset of daylight time each March, there is a measurable increase in suicides , atrial fibrillation , strokes , and heart attacks. Workplace injuries climb. So do fatal car crashes and emergency room visits. Modern society, with its computers, TV-screens, and air conditioning units, uses more energy, no matter if the Sun is up or not. Today, the amount of energy saved from DST is negligible.
One of the aims of DST is to make sure that people's active hours coincide with daylight hours so that less artificial light is needed. This makes less sense close to the equator, where the amount of daylight does not vary much in a year, or near the poles, where the difference between winter and summer daylight hours is very large.
However, at latitudes between these extremes, adjusting daily routines to the shifting day length during summer may indeed help to save energy. A German analysis of 44 studies on energy use and DST found a positive relationship between latitude and energy savings.
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