Driver Knowledge Tests

Are you allowed to drive if you have had blackouts?

A blackout is where you suffer a temporary loss of consciousness. Obviously, when driving a vehicle, this is very dangerous. Blackouts can be caused by a number of physiological factors and chemical factors.

  • Fainting – more than 50% of blackouts are due to this and it’s often caused by hot weather, prolonged standing, having blood taken or experiencing intense emotions
  • Syncope (temporary loss of blood flow to the brain) due to cardiovascular disease or arrhythmias
  • Epileptic seizures (these account for less than 10% of blackouts)
  • Drug intoxication
  • Sleep disorders (e.g. microsleeps)
  • Hypoglycaemia

Drivers will almost certainly need to see a specialist to determine how to manage the blackouts. For fainting (vasovagal syncope) it’s not usually necessary to restrict driving, but a cardiovascular exam may need to be conducted to eliminate any potential heart problems. Specialists will look at the likelihood of it recurring while you drive.

Drivers who develop epilepsy must stop driving until they have been free of seizures for at least 12 months. Drivers should not drive after taking drugs. Drivers suffering from diabetes which caused the hypoglycaemia must follow the procedures here.

Sleep disorders are more insidious. If it was found to be a microsleep then a sleep study might be conducted. Strategies to help drowsy driving include using a CPAP machine, ensuring at least 7-8 hours of sleep a night, changing the mattress, keeping the room temperature comfortable, and not doing shift work. Some factors may be temporary such as a new baby.

When must a driver consider a conditional licence?

The driver licensing authority will take into account the type of driving the driver does. For example, a person that only occasionally is required to drive a medium combination vehicle will be treated differently to a driver driving a multiple combination vehicle across the country, all other things being equal.

If the blackout can’t be diagnosed then the person may not be fit to hold an unconditional licence. If a person doesn’t meet the standard for an unconditional licence because they have had a blackout where the cause can’t be determined, but a specialist is of the opinion that they are safe to drive then they may be eligible for a conditional licence with an annual review.

Private drivers

Where the cause of the blackout is known, if there has been a single blackout or more than one blackout within a 24-hour period, a conditional licence may be considered by the driver licensing authority subject to at least annual review, taking into account information provided by the treating doctor. There must have been no further blackouts for at least six months.

If there have been two or more blackouts separated by at least 24 hours, a conditional licence may be considered by the driver licensing authority subject to at least annual review, taking into account information provided by the treating doctor. There must have been no further blackouts for at least 12 months.

Commercial drivers

The rules are the same as above but the time periods without blackouts are 5 years and 10 years respectively.


Darren is an expert on driving and transport, and is a member of the Institute of Advanced Motorists

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