A university professor says you are simply adjusting your body clock after changing every other timepiece in the house on Saturday night.

And, according to some studies, you are also more likely to have a car accident or heart attack in the next seven days.

Tomorrow is the dawning of daylight savings for another summer.

Clocks will advance one hour from 2am to 3am.

Yes you will lose an hour’s sleep but according to an expert in the field that is just the start of your problems.

Swinburne associate professor Greg Murray, who studies circadian rhythms in mood disorders, says the days and weeks after the changeover can create sleep problems as our bodies adjust to the change in the sleep-wake rhythm.

“Daylight saving is designed primarily to save energy by shifting human behaviours more towards the light phase of the day,” he said.

“But adjusting to the switch can cause sleep disturbances.

“On top of the chronic sleep deprivation that many people suffer, this additional loss of sleep appears to cause decreased alertness, concentration and mental performance.”

The professor says some studies show the sleep loss is to blame for the apparent increase in traffic accidents and heart attacks.

But architects say it is boom time for entertaining.

David Hallett, Victorian state manager of Archicentre said the added hour of daylight extends the use of the home for entertainment and relaxation.

Daylight saving operated nationally during part of World War I and World War II, but it was not observed again in NSW until 1971, when it became a permanent fixture.

Daylight savings will end on April 3 next year.