University of Auckland scientists try to pinpoint the moment sleep deprivation makes us deteriorate

Getting a full eight hours every night isn't always possible and it's no secret a lack of sleep affects the way we function. 

But how much sleep is enough? Scientists at the University of Auckland are trying to pinpoint the moment sleep deprivation makes us lose control of our impulses. 

And they're hoping to put their findings to good use. 

Doctors, nurses, police, and bus drivers are all professions where the ability to be alert and on task is often a matter of life or death.

And their ability will be affected by how much sleep they get or lack.

"We're really looking to find that tipping point where our ability to control impulsive action starts to deteriorate," Dr Arne Nieuwenhuys said.

Researchers at the University of Auckland's Department of Exercise Science are studying sleep deprivation and how it affects how we behave and function. 

Participants are set a seemingly mindless task.

But for study participant Corey Wadsley it's a challenge. 

And that's because he's been kept awake all night by research assistant Kelly Tay. 

"27 hours… been awake for 27 hours," she said.

She's already noticing the difference in varying levels of sleep. 

"They can be with you and playing a board game and they slowly nod off whereas other participants, you can tell they're tired but they're okay and still awake," Tay said.

The participant's ability to control their actions and behaviour is tested across different days after 8, 6, 4, 2 and 0 hours of sleep.  

Dr Nieuwenhuys, who's previously worked with Olympic athletes, gives the example of sitting in traffic and trying to find the point at which a lack of sleep can put us on auto-pilot mode and affect how we react at traffic lights.

"It is just as important to be able to stop action in those moments where it is inappropriate," Dr Nieuwenhuys said.

So after a night of no sleep how does Wadsley think he'd fare behind the wheel?

"No chance, no shot," he said.

An electrical pulse is used to simulate the consequences of not being alert but the consequences in real life could be far worse.

"Where people work in circumstances where there is dire consequences of making errors," Dr Nieuwenhuys said.

And he hopes the findings of his study will help redefine how people in high-risk jobs rest in order to reduce risk.