Maybe having a good sleep after a traumatic event is not the way to avoid on-going stress disorders, scientists now say.

Escaping into sleep may not be the right way of dealing with a traumatic experience, a study suggests.

On the contrary, a period of sleep deprivation may act as a barrier to consolidating bad memories and reduce disturbing flashbacks, scientists found.

Researchers showed study participants a film containing emotionally traumatic scenes before either preventing them from sleeping or allowing them a normal night's sleep at home.

Dr Kate Porcheret, from Oxford University's Nuffield Department of Clinical Neurosciences, said: 'We wanted to see what effect sleep deprivation would have on the development of intrusive memories - what in a clinical setting are called flashbacks."

Each participant kept a diary in which to record intrusive memories, however fleeting, and was asked to provide as much information as possible.

Team member Dr Katharina Wulff said: "The sleep-deprived group experienced fewer intrusive memories than those who had been able to sleep normally.

"Both groups experienced more of these involuntary memories in the first two days and a reducing number in the following days. We know that sleep improves memory performance including emotional memory but there may be a time when remembering in this way is unhelpful."

Further work is needed as flashbacks following traumatic events are still not well understood and real-life trauma cannot be replicated in a laboratory, say the scientists who report their findings in the journal Sleep.

Dr Porcheret added: "Finding out more how sleep and trauma interact means we can ensure people are well cared for after a traumatic event. These are really important research questions to pursue further.

"For example, it is still common for patients to receive sedatives after a traumatic event to help them sleep, even though we already know that for some very traumatised people this may be the wrong approach.

"That is why we need more research in both experimental and clinical settings into how our response to psychological trauma is affected by sleep - and lack of sleep too."