A latest University of Pennsylvania School of Medicine study has found that sleep deprivation leads to more serious health problems than previously thought. Researchers say that sleep loss causes irreversible physical damage to brain cells and even cell death.

Extended periods of sleeplessness observed in shift workers, students, and truckers results in injuries and loss of the locus coeruleus (LC) neurons that are essential for alertness and optimal intellect, say researchers. Catching up on sleep during weekends does not help prevent the long-term damage.

"In general, we've always assumed full recovery of cognition following short- and long-term sleep loss," Dr Sigrid Veasey said in a press release. "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."

Through this study the researchers wanted to find out whether sleep loss harms which neurons whether the damage is reversible.

For the study, researchers followed mice during periods of normal rest, and short and extended wakefulness. Researchers found that during short periods of sleep loss, LC neurons increased the production of sirtuin type 3 (SirT3) protein that prevents injuries to neurons and is important for energy production.

However, during long periods of wakefulness, this protein is not produced. As a result LC neurons showed lower protein levels in sleep deprived mice and increased cell death. In fact, these mice lost 25 per cent of their LC neurons.

"This is the first report that sleep loss can actually result in a loss of neurons," 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."

Veasey said that by increasing SirT3 levels in the mitochondria by some or the other means, medical professionals can prevent injuries and damage to neurons due to lack of sleep.

Previous studies have shown that loss of sleep is linked to obesity and impairs cognitive performance.

The finding is published in the Journal of Neuroscience.