London - It's a discovery to make the highly-strung among us rest a little easier.
Stress can, apparently, boost our brain power.
While chronic stress can increase the risk of heart attack and compromise the immune system, researchers have found that short-lived stress - such as that over an examination or a job interview - primes the brain for improved performance - most notably boosting memory.
In studies on rats, the researchers found that significant, but brief stressful events caused stem cells in the brains of rats to turn into new nerve cells that, when mature two weeks later, improved their mental performance.
'You always think about stress as a really bad thing, but it's not,' said Daniela Kaufer, associate professor of integrative biology at the University of California, Berkeley.
'Some amounts of stress are good to push you just to the level of optimal alertness, behavioral and cognitive performance.
'I think intermittent stressful events are probably what keeps the brain more alert, and you perform better when you are alert,' she said.
Much research has demonstrated that chronic stress elevates levels of stress hormones, which suppresses the production of new neurons in the hippocampus, impairing memory.
It's also known that chronically elevated levels of stress hormones increasing the risk of obesity, heart disease and depression.
But less is known about the effects of acute stress, Dr Kaufer said, and studies have been conflicting.
To clear up the confusion, the researchers subjected rats to what, to them, is acute but short-lived stress – being locked in their cages for a few hours.
This led to stress hormone (corticosterone) levels as high as those from chronic stress, though for only a few hours.
But it also doubled the proliferation of new brain cells in the hippocampus,.
The researchers also found that the stressed rats performed better on a memory test two weeks after the stressful event, but not two days after the event.
Using special cell labeling techniques, the researchers established that the new nerve cells triggered by the acute stress were the same ones involved in learning new tasks two weeks later.
'In terms of survival, the nerve cell proliferation doesn't help you immediately after the stress, because it takes time for the cells to become mature, functioning neurons,' said Dr Kaufer.
'But in the natural environment, where acute stress happens on a regular basis, it will keep the animal more alert, more attuned to the environment and to what actually is a threat or not a threat.'
However the researchers noted that exposure to acute, intense stress can sometimes be harmful, leading, for example, to post-traumatic stress disorder.
'But I think the ultimate message is an optimistic one, concluded Dr Kaufer. 'Stress can be something that makes you better, but it is a question of how much, how long and how you interpret or perceive it.'
The study is published in the online journal eLife. - Daily Mail