Night shifts can cause an irreversible loss of brain cells

AFP

Many shift workers believe they can make up for working nights by having a lie in when they’re not on duty
But new research suggests catching up on missed sleep at the end of the week is not sufficient to prevent long term damage.
The US study revealed chronic sleep loss can lead to irreversible loss of brain cells.
The researchers, at the University Of Pennsylvania School Of Medicine, found sleep loss is linked to injury to, and loss of, neurons that are essential for alertness and optimal intellect.
‘In general, we’ve always assumed full recovery of cognition following short- and long-term sleep loss,’ Dr Sigrid Veasey said. 
‘But some of the research in humans has shown that attention span and several other aspects of cognition may not normalise even with three days of recovery sleep, raising the question of lasting injury in the brain. 
‘We wanted to figure out exactly whether chronic sleep loss injures neurons, whether the injury is reversible, and which neurons are involved.’
The team studied mice following periods of normal rest, short periods of wakefulness and lengthy spells of sleep deprivation.
They found that after short periods of sleep loss neurons increase their production of a protein that is important for energy production and which prevents injury to neurons.
However, after extended periods of wakefulness, this protein is no longer ‘upregulated’.
As a result, sleep deprived mice start to display signs of increased cell death.
In fact, the response is so significant that the mice lost 25 per cent of their locus coeruleus neurons.
The locus coeruleus is in the brainstem and is involved in the physiological responses to stress and panic.
‘This is the first report that sleep loss can actually result in a loss of neurons,’ Dr Veasey said. 
‘Particularly intriguing is that the findings suggest that mitochondria in locus coeruleus neurons respond to sleep loss and can adapt to short-term sleep loss but not to extended wake.’
Dr Veasey says the discovery raises the possibility of treatment aimed at increasing the relevant protein levels in mitochondria in a bid to protect neurons from the effects of extended sleep loss.
Dr Veasey stresses that more work needs to be done to establish whether a similar phenomenon occurs in humans, and to determine what durations of sleep deprivation place individuals at risk of neural injury. 
He added that the body’s response to sleep loss could be affected by ageing, diabetes, a high-fat diet and by lack of exercise.
His team now also plans to investigate whether there is a link between shift work and Alzheimer’s and Parkinson’s diseases.

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