Missing out on sleep may cause the brain to stop producing new cells, a study has suggested.

The work on rats, by a team from Princeton University found a lack of sleep affected the hippocampus, a brain region involved in forming memories.

The research in Proceedings of the National Academy of Science showed a stress hormone causes the effect.

A UK expert said it would be interesting to see if too little rather than no sleep had the same consequence.

Deficits

The researchers compared animals who were deprived of sleep for 72 hours with others who were not.

They found those who missed out on rest had higher levels of the stress hormone corticosterone.

They also produced significantly fewer new brain cells in a particular region of the hippocampus.

When the animals' corticosterone levels were kept at a constant level, the reduction in cell proliferation was abolished.

The results suggest that elevated stress hormone levels resulting from sleep deprivation could explain the reduction in cell production in the adult brain.

Sleep patterns were restored to normal within a week.

However levels of nerve cell production (neurogenesis) were not restored for two weeks, and the brain appears to boost its efforts in order to counteract the shortage.

Writing in PNAS, the researchers led by Dr Elizabeth Gould, said that although the role of nerve cell production in adults remained unknown, "the suppression of adult neurogenesis may underlie some of the cognitive deficits associated with prolonged sleep deprivation."

People who experience a lack of sleep experience concentration problems and other difficulties.

Sleep expert Dr Neil Stanley, based at the Norfolk and Norwich University Hospital, said the study's findings could not be directly translated to humans because people did not go without sleep for 72 hours, unless they were in extreme circumstances.

But he added: "It is an interesting finding. It would be interesting to see if partial sleep deprivation - getting a little bit less sleep every night that you need - had the same effect."

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