The Reason for Daylight Savings and the Relativity of Time

Moving the clock an hour forward is an excellent day of the year for me because it means that we can enjoy more daylight. Instead of sleeping through the first hours of daylight, I wake up close to when the sun rises, allowing me to get most out of my day. This blissful state unfortunately only lasts for about six months as the clocks eventually are moved back again.

I am writing this article from Coolangatta, on the border between New South Wales and Queensland in Australia. The border runs through the middle of the built-up area and without there is no real indication which part of the street is in which state. Queensland does not observe daylight-saving, which means that there is a one-hour time difference between one side of the road and the other. Crossing the street is like travelling backwards and forwards in time, without having to worry about time travel paradoxes. You can safely kill your grandfather without vanishing into thin air. In Coolangatta and Tweed Heads you can even be in two time zones at the same time, without being ripped apart by temporal tidal forces.

Daylights savings is a controversial subject and article discusses some of the reasons that people love daylight savings and some of the arguments against the bi-annual timeshift.

The Reason for Daylight Savings and the Relativity of Time

The Reason for Daylight Savings

Daylight savings makes perfect rational sense for an urbanised population at a fair distance from the equator. Why would anyone want to sleep through the first hours of daylight during summer? The original argument for daylight savings was to save energy because people would spend less time in the dark and require less illumination. If there is more sunlight at the end of the day, there will be less time we are awake in the dark. Although that might be logically correct, there are so many other factors that influence energy consumption that the effect of daylight savings is minimal. Also, the cost of illumination is now so small that it hardly matters anymore.

The best reason for daylight savings is that sunlight is good for your health, even when you are indoors. Natural light positively impacts our mood and has been shown to improve performance. Spending the first hours of daylight in bed thus seems to be an awful waste. In an industrial society where most people spend their time indoors, it makes perfect sense to maximise the amount of daylight they can use.

The Unreason of Daylight Savings

Some people struggle with the concept of changing time zones during the warmer months. There are reports of people that have a mini-jetlag due to the changes. There are, however, also individuals who struggle intellectually with the concept of time changes. Some people seem to think that the very act of moving the clock an hour forward implies that we are adding an hour of daylight to the day. They appear to believe that changing the reference point of our clocks somehow influences the rotation of the earth. The amount of daylight does obviously not alter during daylight savings. Changing our clocks optimises how we use the available sunlight.

The letter shown below was written to a regional newspaper during the height of the Millennium Drought that almost crippled southern Australia. The author blames the dire situation of those days on daylight savings. He claims that the extra hour of sunlight is “slowly evaporating the moisture”. Evaporation indeed increases in summer, but changing the clocks is not the cause of the problem.


The Reason for Daylight Savings and the Relativity of Time


Measuring Time

Coolangatta and Tweed Heads illustrate that time is relative, not only in the physical sense of Einstein’s special theory of relativity but also in the social sense. The time of day is not the result scientific research but is agreed by social convention. Time is whatever we decide it to be so that we can have a functioning society where people can do things simultaneously.

Our clock is defined by 24 hours in a day, divided by noon. Each hour has sixty minutes, each of which has sixty seconds. This system might seem strange as it would make more sense to have two times ten hour days with 100 minutes per hour and 100 seconds per minute. The clock with two periods of twelve hours has its roots in the sexagesimal number system used by the Sumerians five thousand years ago. This system uses sixty digits instead of our system based on ten digits. The Sumerians used this method because sixty is divisible by many numbers, which helps with accurate calculations without decimals. We have inherited this number system in the way we measure trigonometry and time. It is incredible to realise that the way we measure time has not changed much in five thousand years!

In the Roman Empire, time was based on sunset and sunrise, measured with a sundial. The day was divided into twelve hours, which meant that the length of an hour varied over the course of a year, depending on your location within the empire. At the Forum Romanum, an hour was about 45 minutes in winter an 75 minutes during summer. Further north, near Hadrian’s wall, an hour was between 35 and 85 minutes.

By Ad Meskens (Own work) [Attribution, CC BY-SA 3.0 ( or GFDL (], via Wikimedia Commons

Roman sundial. Photo by Ad Meskens via Wikimedia Commons.

With the invention of mechanical clocks, the day became divided into 24 hours of equal length. Hours of equal length are easier to comprehend, but the downside is that the times for sunrise and sunset are always shifting. The changing time for dawn was not a problem in agricultural societies as they tend to manage their time based on available sunlight.

Before official time zones existed, each village kept its own time with minor differences between them. The official time was whatever was displayed on the local church clock, with noon defined by the highest position of the sun. This system worked fine for centuries, but with the invention of instant communication, it became necessary to synchronise the clocks around the country and formal time zones came into existence.

Perhaps we can use technology to solve the daylight savings problem. The way we measure time during the day has changed once before; maybe we should change it again. We could develop electronic clocks that synchronise sunrise to always occur at six or seven in the morning. The time between successive sunrises then defines the 24-hour day. This new system provides daylight savings every day of the year, with only a gradual daily change each day.

Implementing this method would be a gigantic task which dwarfs the issues we had with the Millennium Bug. Perhaps it is time to modify the way we measure time for a third time in the past five thousand years to maximise our daylight, aided by technology.

Peter Prevos

Social scientist and engineer who dabbles in magic tricks.

2 Responses

  1. Sky says:

    Nice 👌

  1. 27 May 2018

    […] key to Balinese water management is the way they measure time. The Balinese calendar is a complex interaction between two different ways to measure the passage […]

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