Daylight savings time is kind of confusing. To be honest I didn't
know much about it until I looked it up on the wikipedia. It has
information Arizona and agriculture that is relevant to what we've been
discussing. Here's
the relevant excerpt:
"
Rationales for DST
One of the major reasons given for observing DST is energy
conservation. Theoretically, the amount of residential electricity
needed in the evening hours is dependent both on when the sun sets and
when people go to bed. Because people tend to observe the same bedtime
year-round, by artificially moving sunset one hour later, the amount of
energy used is theoretically reduced.
United States Department of Transportation studies showed that DST reduces the country's electricity usage by one percent during each day DST is in effect.
Part of the reason that it is normally observed in the late spring,
summer, and early autumn is because during the winter months the amount
of energy saved by moving sunset one hour later is negated by the
increased need for morning lighting by moving sunrise by the same
amount. During the summer most people would wake up after the sun
rises, regardless of whether daylight saving time is in effect or not,
so there is no increased need for morning lighting to offset the
afternoon energy savings.
Another perceived benefit of DST is increased opportunities for
outdoor activities. Most people plan outdoor activities during the
increased hours of sunlight. Other benefits cited include prevention of
traffic injuries (by allowing more people to return home from work or
school in daylight), and crime reduction (by reducing people's risk of
being targets of crimes that are more common in dark areas).
When the U.S. went on extended DST in
1974 and
1975 in response to the
1973 energy crisis,
Department of Transportation studies found that observing DST in March
and April saved 10,000 barrels of oil a day, and prevented about 2,000
traffic injuries and 50 fatalities saving about U.S.
$28 million in traffic costs. (Stats from
this article).
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<a name="Criticism_of_DST" id="Criticism_of_DST"></a>
Criticism of DST
DST is not universally accepted; many localities do not observe it.
Opponents claim that there is not enough benefit to justify needing to
adjust clocks twice every year. The disruption in sleep patterns
associated with setting clocks either forward or backward correlates
with a spike in the number of severe auto accidents,<sup id="ref_autoaccidents" class="plainlinksneverexpand">
[1]</sup>
as well as lost productivity as sleep-disrupted workers adjust to the
schedule change. It is also noted that much effort is spent reminding
everyone twice a year of the change, and thousands are inconvenienced
by showing up at the wrong time when they forget.
There is also a question whether the savings in lighting costs justifies the increase in summertime
air conditioning
costs. While most people use more sunlight under DST, most people also
experience more heat, which prompts many people to turn on the air
conditioner during the warmer afternoon hours. When air conditioning
was not widely available, the change did save energy; however, air
conditioning is much more widespread now than it was several decades
ago. Air conditioning often uses more energy than artificial lighting.
It was for this reason that Arizona rejected DST and opted to stay on
standard time all year.
It is also speculated that one of the benefits, more afternoon sun,
would also actually increase energy consumption as people get into
their cars to enjoy more time for shopping and the like.
No formal studies have been performed, but an enormous amount of
time has been spent by software developers to deal with the fact that
2400 hours past 2pm is not necessarily 2pm 100 days later.
For example, during a North American time change, an autumn night
where clocks are reset from 3 AM summer to 2 AM winter time, times
between 2AM and 3AM will occur twice, causing confusion in transport
schedules, payment systems, etc.
Some studies do show that changing the clock increases the traffic
accident rate. Following the spring shift to Daylight Saving Time (when
one hour of sleep is lost) there is a measurable increase in the number
of traffic accidents that result in fatalities. Some suspect that the
change in lighting conditions confuses drivers in their regular
commutes. Others speculate that it relates more to the amount of sleep
a person gets. Still others suspect that people hurry because they have
looked at an incorrect clock and discover that they are late. And a few
even suggest that the traffic accidents are caused by people trying to
reset the clocks in their cars while driving.
Some campaigners in
Britain would like the country to stay on
British Summer Time (BST) all year round, or in other words, adopt
Central European Time
and abolish BST. Alternatively, some would like Britain to adopt
Central European Time and jump forward another hour during the summer
(adopting a Single/Double Summer Time from Britain's perspective). This
would make winter evenings longer, thereby reducing traffic accidents
and cases of
seasonal affective disorder. Opponents point to the longer hours of darkness on winter mornings, especially in
Scotland,
which might well cause an increase in road accidents. It has even been
suggested that Scotland should be placed on a different
time zone from the rest of the UK, which, unlikely though it may sound, would be possible as the
UK Parliament could legislate to put the UK forward an hour, and then the
Scottish Parliament could put Scotland back onto GMT.
DST is particularly unpopular among people working in
agriculture
because the animals do not observe it, and thus the people are placed
out of synchronization with the rest of the community, including school
times, broadcast schedules, and the like."
Source:
http://en.wikipedia.org/wiki/Daylight_saving_time