总发困？怨父母!

Whether you prefer burning the midnight oil or going to bed early so you can get up at the crack of dawn depends on your genes, according to experts.

I leap out of bed each morning, keen to start an active day. But I can hear my neighbour's alarm clock ringing non-stop every morning and I doubt he gets to work on time.

A lot of noise comes from his flat in the evening. He's happy to stay up watching telly till the wee small hours, while I turn in early and try to sleep.

Well, it might not be his fault after all. Neurogeneticist Dr Louis Ptacek of University of California would say I'm 'a lark' and my neighbour is 'an owl'. Families of 'extreme owls', with Familial Delayed Sleep Phase syndrome, were found to have a different mutation in the same genes.

We all have internal 'clocks' located in the part of the brain which controls all kinds of bodily functions and it is reset every day by light. These internal clocks run to a different schedule in 'larks' and 'owls'. If you have a fast clock, you like to do things early, and if you have a slow clock, you like to do things late.

Because we live in a 24/7 world, scientists believe it's important to understand a person's 'chronotype' – the time of the day when they function the best. It could help us lead a healthier life.

Prof Till Roenneberg of Ludwig-Maximilians University in Munich has studied sleeping patterns and thinks work times should be changed and made more individual to fit in with our chronotypes.

And he has advice for those who can't choose their work shifts: "If that's not possible, we should be more strategic about light exposure", says Prof Roenneberg. "You should try to go to work not in a covered vehicle but on a bike. The minute the sun sets we should use things that have no blue light, like computer screens and other electronic devices."

So what about you? Are you 'a lark' or 'an owl'?