We've all been there: not enough sleep, brain is foggy and you're struggling to put two and two together.

So what happens to our brain to make us do odd things when we don't get enough shut eye?

Key points: Sleep deprivation impairs the brain and affects reaction time and memory function

Sleep deprivation impairs the brain and affects reaction time and memory function Eight hours of sleep plus 10-15 minutes extra to fall asleep is the perfect amount of rest

Eight hours of sleep plus 10-15 minutes extra to fall asleep is the perfect amount of rest Napping for as little as 10 minutes can help increase cognition and reflexes

Often when we are exhausted we do things we normally would not do, for example putting the car keys in the freezer.

Recently Queensland Tourism Minister for Innovation and Tourism Development Kate Jones tweeted that she used foot cream as toothpaste without realising because she was so tired.

"As working parents you're always exhausted and I thought it was a new toothpaste," she told ABC Radio Brisbane.

"I was trying to do two things at once, trying to get the three minutes in, before I realised it didn't taste so good.

"It took me a while to register that the tubes were the same size, shape, and colour but one was toothpaste and the other was peppermint foot revival cream."

Loading

A report released earlier this year by the Sleep Health Foundation showed that nearly 40 per cent of Australians experienced some form of inadequate sleep.

Sleep unit manager at the Wesley Hospital's Sleep Disorders Centre, Phil Teuwen, said a lack of sleep made it difficult for brain cells to communicate effectively.

"Sleep deprivation impairs the brain and affects your reaction time, cognition, and memory function," he said.

"All those things can deteriorate if you have poor quality sleep.

"We know that after a night shift, when you're driving home, your impairment is equal to, or greater than, someone who has a .05 blood [alcohol] level."

When the body is starved for sleep, it robs neurons of the ability to function properly causing temporary mental lapses that affect memory and visual perception.

"Many companies have fatigue management now as it's really important for professions such as doctors who have long hours and make high-level important decisions when they are quite sleep deprived," Mr Teuwen said.

Can people adjust to a lack of sleep?

Mr Teuwen said everyone was different when it came to the impact a lack of sleep had on people.

"You can live longer without food than you can without sleep," he told ABC Radio Brisbane's Rebecca Levingston.

"Anyone that has tried to break the record of staying awake the longest has experienced hallucinations as cognitive decline is inescapable."

He said naps were often seen as taboo in modern culture.

"We know that having a nap increases your cognition and reflexes, memory recall, and all those things," Mr Teuwen said.

"We should nap more and nap pods are common in many work places now."

He added that when driving long distances, it was better for people to try and pull over and have a 10-minute nap even if they didn't fall asleep.

"A former colleague of mine did a study and discovered a Driver Reviver didn't improve your ability to drive, but what did improve it was trying to have a nap, even for 15 minutes," Mr Teuwen said.

"If you're on a long drive and feel tired, pull over and attempt to have a sleep and it will really improve your concentration."

Mr Teuwen said the current theory behind the 'right amount of sleep' was still eight hours, plus a little more.

Making sure you get over 8-hours sleep will help you get through your day. ( Unsplash: Vladislav )

"Eight hours was the main aim for sleep, then it ranged from seven to 10 hours, but it varies for everyone," he said.

"Now the current thinking is to add 10 to 20 minutes to falling asleep then have eight hours after that."

Your lack of sleep stories

Callers and comments to ABC Radio Brisbane showed the variety of things that happen when we struggle to get a good nights sleep.

"I was going to a conference and just had a new baby and I put on a black and brown shoe and didn't realise until I was on the plane." — Andrew from Cleveland

"Condensed milk in a tube came out in the 1960s and we were out walking, and someone put hand cream in instead of the condensed milk." — Allie from Kenmore

"I used hairspray as a deodorant. It made for sticky underarms." — Sandra Farrell

"I once used sunscreen instead of toothpaste — yuck!" — Caroline Scott