Daylight Saving Time (DST), (yes — there’s no “s” there) the annual practice of shifting the clocks by an hour each fall and spring, is as unpopular a practice as it is controversial. When the idea was first formally adopted in 1918 by the U.S. Congress, it took less than a year to be repealed later in 1919. However, we couldn’t kick the idea of changing our clocks completely, and in 1966, Daylight Saving Time was signed into law with the Uniform Time Act and different localities could observe the practice on a whim and at any date or time they wanted!

While some have their own theories of how Daylight Saving really began, it's actually a myth that farmers created the bi-annual time change to have more sunlight hours to work in the fields. In reality, farmers work with the sun, so they don't give a fig about clocks. And, since 1966, the biggest champions of Daylight Saving observance have actually been corporations and retailers who want to save money on energy costs and shift the clocks in accordance with the seasons in order to do so.

However, recent research cited on CNN.com demonstrates the electricity savings during DST are negligible thanks to increased heating and cooling costs.

Daylight Saving and Sleep

But, why is it such a big deal when it comes to our sleep?

What does the daylight saving practice actually mean?

Think back to fifth-grade science class: We all learned that we experience seasonal changes thanks to the earth's rotation and its tilted axis. In the northern hemisphere, we experience spring/summer in the months when the earth is tilted toward the sun and fall/winter when the earth is titled away. The days naturally get longer and shorter, and our bodies respond in kind.

However, when Daylight Saving is in effect between March and October, the sun rises (again, according to the clock) an hour earlier and later than it normally would. So, by adopting daylight saving time, we actually get more "clock daylight" in the mornings and afternoons.

Okay, how does it affect sleep?

You may think, "Okay, big deal. Every weekend I may gain or lose an hour of sleep depending on the schedule of my work, family, and social life."

And it's true, individual sleep schedules can vary widely (although keeping to a consistent sleep schedule is often cited as one of the most crucial keys to good health), but our systems get so thrown off by DST, not so much by the shifting hours but rather by the changing of light and our exposure to the sun.

Why, you ask? Everyone's hypothalamus hosts a suprachiasmatic nucleus (SCN). The SCN regulates time in your own body via hormones and chemicals, regardless of the time on the traditional clock. You can thank the suprachiasmatic nucleus for acting as a giant clock and "keeping time" for your entire body, including liver and immune functions and circadian rhythms.

So, when the hormones and chemicals the SCN uses to "keep time" for your body are influenced by external factors such as food, temperature and sunlight, we can begin to feel “off” like we generally do right after we change our clocks forward. As such, that is why when Daylight Saving Time occurs, and our bodies get less light in the morning and more in the evenings (initially), our suprachiasmatic nucleus is thrown into temporary chaos.

A very similar thing happens during "jet lag" when our sleep and wake cycle shifts due to time zones.

Is it just "spring forward" that messes with our sleep?

In general, "springing forward" actually gets a bad rap. Even when we gain an hour when the clocks "fall back" in November, our sleep cycles can be disrupted just as much.

Experts caution that both sleep losses and gains can affect the body and mind adversely for up to five to seven days. And, research supports that most don't even get to indulge in that extra hour of sleep when DST ends. WebMD reports only four out of 10 Americans use the extra hour for sleep, and of those who use the sun to wake naturally, a majority end up waking up around the same time as normal.

But yes, we tend to "feel" the effects of daylight saving more in the spring when we lose that precious hour, and it becomes darker in the mornings at the time we're used to waking.

So, what can we do about losing/gaining sleep during Daylight Saving?

The Sleep Foundation recommends treating DST related grogginess in many of the same ways we treat jet lag: with good, thorough exercise. You can also set your alarm a half-hour earlier in the AM and later in the PM to expose your brain to more sunlight in the week following the spring forward and fall back.

However, for those who just can't stand Daylight Saving, rest assured that each year there is more and more research available to prove DST doesn't actually save on energy and that it is likely detrimental to human health. In fact, many locales like Florida, California, and the New England states are mounting legislation to keep Daylight Saving Time in effect year-round.