By Geraldo Rizzo, MD
The idea of daylight-savings time (DST) was, for the first time, attributed to Benjamin Franklin, who anonymously published a letter suggesting that Parisians economize on candles by rising earlier to use the morning sunlight. This 1784 satire proposed taxing shutters, rationing candles, and waking the public by ringing church bells and firing cannons at sunrise. Some say Franklin suggested this to help people to save the money spent on candles during summer.
Modern DST was first proposed by the New Zealand entomologist George Vernon Hudson, whose shift-work job gave him leisure time to collect insects, and made him aware of the value of after-hours daylight. In 1895 he presented a paper to the Wellington Philosophical Society proposing a two-hour daylight-savings time shift. After considerable interest was expressed in Christchurch, New Zealand, he followed up by writing a paper on the subject in 1898.
This suggestion by Mr. Hudson was not taken seriously up until the beginning of the First World War. Starting on April 30, 1916 Germany and its World War I allies were the first to use DST (known as “Sommerzeit”) as a way to conserve coal during wartime. Britain, most of its allies and many European neutrals soon followed suit. Russia and a few other countries waited until the next year and the United States finally adopted it in 1918. This practice was repeated during the Second World War, when England applied the double daylight savings time, advancing time two hours, to maximize the use of natural light. After the war ended, a great number of countries kept that system and nowadays there are approximately thirty who have adopted it. However each country has chosen different periods to start and end the daylight saving time.
The effects of DST on the body are similar to an airplane trip crossing a time zone, the beginning being in an east-west direction (“Spring Forward”) and the end in the west-east direction (“Fall Back”). In normal conditions several rhythms of our body (e.g. temperature, sleep-awake, etc) are synchronized between themselves (internal temporal order) and the bright-dark ambient. With this DST change, our body tries to synchronize its rhythms to the new schedule. However, as each person’s body rhythm has its own speed of adjustment, the phase relation is modified (internal temporal disorder) which can cause the person to not adapt well to the time change. After some days or even weeks (depending of the individual), the internal temporal order is re-established.
During this internal temporal disorder phase, the individual may experiment sleep difficulty, diurnal sleepiness, humor alteration, alimentary habits change, inattention and even accidents. That is the reason why many Sleep Specialists believe that the energy saving is not worth the health cost.
About the Author:
Dr. Geraldo Nunes Vieira Rizzo is a Neurologist, with a postgraduate degree in Clinical Neurophysiology, and is a specialist in the Medicine of Sleep. Member of the American and Brazilian Association of Sleep Medicine, Dr. Geraldo Rizzo is one of the Directors of the Institute of Clinical Neurophysiology at both the Moinhos de Vento and Mãe de Deus Hospitals and is also responsible for the SONOLAB – Laboratory of Sleep, all in Porto Allegre, Brazil.
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Tags: daylight savings time, insomnia, internal temporal disorder, REM sleep, safety, sleep conference, sleep cycle, sleep deprivation, sleep disorder, sleep study