Most smartphone devices and computers automatically adjust the time.

However, clocks needed to be manually moved forward one hour in NSW, Victoria, Tasmania, South Australia and the ACT because daylight saving started early on Sunday morning.

A way to remember how to change clocks for daylight saving is 'spring forward' at the start, and when it ends in autumn, it's 'fall back'.

The change in time means Australia's three standard time zones are now split into five, and Western Australia falls three hours behind those states that observe DST.

Dr Sveta Postnova, from the University of Sydney's School of Physics, said the time change can impact our sleep and circadian rhythm longer than the initial one hour lost overnight.

"Experimental data suggests a cumulative effect of sleep loss lasting for at least the following week and sometimes longer," Dr Postnova said.

Australian Associated Press