Vyazovskiy and his team were surprised to find that some parts of the brain of sleep-deprived mice also exhibited sleep-like activity when they were awake, reports Horizon Magazine.

‘We always thought that this type of activity happens only during sleep,’ said Dr Vyazovskiy. ‘But it’s as if you can be asleep and awake at the same time.’

In other experiments, they looked at the effects of sleep deprivation on behaviour. The animals were taught to recognise different images and their ability to tell them apart was later tested when they were tired. They found that the mice only had trouble with the task if the two images were very similar. ‘It seems like sleep deprivation only affects cognitive abilities that require significant effort,’ said Dr Vyazovskiy. Routine tasks are less likely to be affected.