Everything you need to know about daylight saving
As we prepare to set our clocks back an hour on 1 April, we asked academics to dispel the myths behind the time change to help us understand its relevance today, over 100 years since it was first observed in Germany during World War I.
Daylight saving is a result of the earth鈥檚 tilted rotation around the sun
鈥淭he Earth's axis of rotation is tilted, which means that the sun rises and sets at different times throughout the year as the Earth moves around the Sun,鈥� says聽聽from the聽. 鈥淭he result is that days are longer in summer than in winter.鈥�
鈥淭he effect of daylight saving time (DST) becomes less as you move towards the equator, which is presumably why Queensland decided not to adopt daylight saving.
鈥淲ithout adjusting the clocks, we would find sunrise in Sydney varying from about 4:30am in summer to 7am in winter. Given this variation, we put the clocks forward by one hour during summer months, so that the earliest sunrise is about 5:30am.
鈥淎s a result, it remains lighter in the evening during daylight saving time, the sun sets at around 8pm.鈥�
All four southern states observe daylight saving
鈥淧lebiscites have been held on daylight saving in Western Australia in 1975, 1984, 1992 and 2009, with a majority voting 鈥楴o鈥� each time.聽 Queensland also voted 鈥楴o鈥� in 1992,鈥� says Professor of Constitutional Law, , from the .
鈥淭he consequence is that both Western Australia and Queensland do not currently have daylight saving, as is also the case in the Northern Territory. In contrast, New South Wales voted 鈥榊es鈥� in 1976 and South Australia voted 鈥榊es鈥� in 1982, so all four southern states have daylight saving.
鈥淲hile some regard the different time-zones as annoying, they actually reflect one of the great benefits of federalism 鈥� that people in different geographical parts of Australia can choose the system that best suits their own circumstances.
鈥淚n a large geographically and climatically diverse country, one size does not necessarily fit all and should not be imposed upon all.鈥�
The time change impacts our sleep and circadian rhythm
鈥淢oving our non-biological clocks by an hour due to daylight saving time (DST) shifts our daily activities and thus the exposure to light and other time cues relative to our internal circadian clocks. This introduces a minor circadian misalignment,鈥� says聽聽a Lecturer in Brain Dynamics and Neurophysics from the School of Physics.
鈥淩elative ease of adjustment to minor time changes are assumed by the general population, however scientific data does not support this.
鈥淔or the spring transition with one-hour sleep loss on the night of the transition, experimental data suggests a cumulative effect of sleep loss lasting for at least the following week and sometimes longer. The autumn transition is popularised as adding one-hour to sleep time, but data shows no evidence of extra sleep on that night.
鈥淚nstead, cumulative sleep loss is also reported in the days following the transition. Overall, DST appears to interfere with natural physiological adaptation to seasonal changes.鈥�
Internal clock misalignment may affect eating temporarily
"Pushing the clocks forward an hour results in a misalignment in our internal biological clock 鈥� otherwise known as our circadian rhythm," says Dr a weight loss expert from the .
"This is a temporary effect, but when it comes to food, you may find yourself eating later in the evening and doing other activities to fill the daylight hours. This can have a flow on effect, especially if you鈥檙e a morning lark and like to get to bed early, and particularly relevant for those who already suffer from digestive problems. If you eat close to bedtime, it can acerbate problems with digestion and reflux, worsening your sleep.
"Try to stick to your normal routine when it comes to portion sizes to improve sleep quality and weight control, make breakfast your largest meal of the day and dinner your smallest."
A farmer's harvest is not affected by daylight saving聽
鈥淔armers' harvest based on the moisture content of the grain, or, if harvesting pastures for hay or silage then it鈥檚 the moisture content of the grasses and plant species in those pastures that鈥檚 important. The time of day is irrelevant,鈥� says Dr Lindsay Campbell, a Senior Lecturer from the聽.
鈥淚t鈥檚 temperature and humidity that will affect harvesting most rather than time. This is why you will sometimes see our farmers at Narrabri out with the lights on after 8pm harvesting. Artificial lighting can be utilised to ensure harvesting occurs at peak turgidity.鈥�
Cows like routine but prefer independence and freedom聽
鈥淐ows like routines and therefore any sudden change (for example, milking one hour earlier) will be noticeable in terms of milk production,鈥� says聽, a Professor of Dairy Science and Director of the聽聽at the聽.
鈥淗owever, milk secretion in the mammary gland is a continuous process. Provided no changes in total feed availability, the effect of a change to milking intervals should be compensated in the next milking and/or become unnoticeable in just a few days.
鈥湼咔甯＠� in robotic milking, where cows get milked by robots whenever they want during day or night, show that cows like more the independence and freedom than the actual routine,鈥� says Yani.
鈥淕iven the choice, some cows would come back to get milked 3 or more times per day, while some others prefer only once or 3 times every 2 days and anything in between.鈥�
Daylight saving better aligns power consumption
鈥淒aylight savings shifts the power consumption an hour forward, so demand is better aligned with solar insolation,鈥� says聽聽from the聽聽in the聽
鈥淵ou don鈥檛 turn your air conditioning off when the sun goes down on a hot day,鈥� explains Professor Verbic, so it鈥檚 not necessarily accurate to suggest air conditioning use will increase as a result of daylight saving 鈥� you're probably running a cooling system regardless.
