People who boast about getting by on less than five hours sleep a night could be doing themselves serious harm, a neuroscientist has said. Russell Foster, a professor at the University of Oxford, said lack of sleep is dangerous in that many early risers try to function with brain skills as impaired as those of a drunk.Studies suggest that working night shifts speeds ageing and is linked to increasing risks of cancer, heart disease and type two diabetes.Foster called for a change in attitudes about early nights.He said sleep deprivation could cause risks not just in jobs such as healthcare and transport, in which the dangers were obvious, but could damage the quality of crucial decisions."We see this too much with really senior people," he said. "Lack of sleep damages a whole host of skills.""Look at the recent decisions about the Greek crisis," he said. "We see major discussions going throughout the night which have a massive impact, and decisions are being made when skills are very impaired." ..