Did you know? A micro sleep can last up to 30 seconds.

US researchers have found that when brains are fatigued, individual brain cells can sleep for a few moments while the rest of their brain functions normally, causing us to make simple mistakes.

Tests performed on sleep-deprived rats showed the regions of their brains fell asleep despite animals being awake. Scientists used to think our brains could only sleep as a whole, which is what happens when people have micro sleeps behind the wheel.

This discovery means there are now earlier signs that your brain is fatigued. So, if you put the wrong key into your cars ignition by accident, you may want to think twice about driving.