YOUR BRAIN ON EXHAUSTION

When you’re tired, judgement, memory and creativity become impaired, and your reflexes can slow down as if you’re drunk.

This helps explain why around 20 per cent of all fatal car accidents in Australia are attributed to tiredness. Much of the decrease in our ability to think happens because we slip into the odd state of ‘local slow-wave sleep’, which is when we appear to be awake but part of the brain is snoozing,

Dr Wu says. Mental illnesses can also worsen with – and maybe even be caused by – not getting enough sleep, experts say. Scientists used to think it was depression or psychosis that kept sufferers awake, but now they believe the neural networks of normal sleep and mental health are intertwined. Stabilising sleep in people with, or vulnerable to mental illness, can break this cycle, says Russell Foster, a British professor of circadian neuroscience at the University of Oxford.