Western Australia · Theory Test (CTT) · Road rules

What is the 'body clock' and why does it matter for driving?

The answer

  • The legal limit on continuous driving hours
  • A measure of reaction time
  • A device fitted to heavy vehicles
  • A natural biological cycle of 24 to 26 hours that programs you to sleep at night Correct

Why that's the answer

Your body runs on a natural biological cycle of 24 to 26 hours, programming you to sleep at night and stay awake during the day. It also dips your alertness for a couple of hours after lunch — which is why afternoon drives can catch you out.

Where this rule comes from

Take the full Western Australia practice test (95 questions)

More WA Learners questions

Same topic first — road rules trips up more learners than any single rule.

Ready for the road?

Once you pass your Theory Test (CTT), you'll need 50 supervised hours in Western Australia. Find an instructor with transparent pricing and live availability.

Find a driving instructor near you