Sleep is important to clear away brain cell 'wear and tear', however, a study found insufficient shut eye causes the system to go into overdrive and also remove healthy nerve cells.

Study author Dr Michele Bellesi, from Marche Polytechnic University, Ancona, Italy, said: 'We show for the first time that portions of synapses are literally eaten by astrocytes because of sleep loss.'

Synapses allow nerve impulses to be communicated between cells, while astrocytes are cells in the central nervous system that 'clean' the brain.

Previous research suggests the removal of nerve cells has been linked to conditions like Alzheimer's disease.

How the research was carried out   

The researchers analysed four different groups of mice.

Rodents in one of the groups were fully rested by being allowed between six and eight hours sleep.

Other animals were woken spontaneously. 

The third group was sleep deprived by being kept awake for eight hours, while the fourth was chronically sleep deprived by not being allowed to nod off for five consecutive days.

Sleep deprivation 'eats' nerve cells  

In sleep-deprived mice, astrocytes 'eat' part of their synapses, the New Scientist reported. 

Rodents who are sleep deprived for eight hours have astrocytes in 8.4 per cent of their synapses, while those that chronically miss out on sleep have them in 13.5 per cent.

This is compared to just 5.7 per cent in well-rested mice and 7.3 per cent in those that are spontaneously awoken.

It is unclear if sleep deprivation has the same effect in humans or if it can be reversed by catching up on shut eye.

The findings were published in the Journal of Neuroscience. 

Less than eight hours sleep is linked to anxiety and depression   

This comes after research released last January suggested getting less than eight hours sleep is linked to anxiety and depression.

Insomniacs are less able to overcome negative thoughts than those who get sufficient shut eye, a study found.

Being unable to nod off also reduces people's ability to disengage from negative emotions, the research adds.

Study author Professor Meredith Coles, from Binghamton University, New York, said: 'We found that people in this study have some tendencies to have thoughts get stuck in their heads, and their elevated negative thinking makes it difficult for them to disengage with the negative stimuli that we exposed them to.

'We realized over time that this might be important - this repetitive negative thinking is relevant to several different disorders like anxiety, depression and many other things.' 

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