The Government has decided to extend daylight saving from next year for reasons that are spurious at best. I am not aware that there has been a huge clamour from busy commuters for early-evening barbecues in April and September. It's a nice idea to think of April as summer, but it's a delusion.

Children will not benefit much from extra evening daylight in March and April. And it's hard to see how more darkness in the morning, when it's cold, is going to save on electricity and other forms of energy.

I teach an economics class at 8.30am two mornings a week. Before that I have to take my son to primary school.

The last weeks before the April holiday are particularly important learning weeks for my students and for my son. In late March my students must sit a 90-minute test at 8.30am. It will do them no favours if the sun doesn't rise until 7.30 am.

In 2008, daylight saving will end on April 6. Consulting the Herald's Sun, Moon and Tide tables for 2007, the sun rose on April 6 at 6.38am; that's 7.38am with daylight "saving".

Compare that with the winter solstice, June 22, which has a sunrise at 7.34am.

Yes, the sun will rise later in our "extended summer" than it will in the middle of winter.

Sunset on April 6 (Easter Saturday this year) occurred at 6.10pm. It would be 7.10pm with daylight saving. That's basically the evening meal time. It's hard to see that many of us will use that hour - between 6pm and 7pm - any differently whether we have daylight saving or not.

The problem won't be so bad in late September. A 6am sunrise will become 7am, an acceptable time for primary school children to wake up. While it's not clear that an extra hour of daylight in the late September evening is more valuable to most of us than it is in the morning, the real problems will occur in late March and early April.

Let's consider four issues that relate to the use of time at the beginning and end of the day: school children's activities, commuting, energy use and recreation.

Children seem to synchronise pretty well with the sun. That's okay in the summer holidays because they can sleep in in the mornings if they need to. In late March children will come inside at around 6pm, whether or not the sun is about to set, but will tend to go to bed later if there is extended evening daylight.

Is it not good for educational outcomes if we have to wake children on dark and often cold mornings in late March and early April. The darkness just compresses the early-morning rush.