Lack of sleep can lead to euphoria – but there’s a downside.

WRITTEN BY JULIET MIMI ATEDZE

Scientists have found that, far from being moody after missing a night’s sleep, we can sometimes get a feeling of pleasant euphoria.

However, the bad news is that this lesser-known effect is short-lived, and can lead to addiction and erratic behaviour. The research has come from boffins at University of California, Berkeley, and Harvard Medical School who say the euphoric effect can also potentially lead to poor judgement. Science News quotes Matthew Walker, associate professor of psychology and neuroscience at UC Berkeley and the study’s chief author, as saying: “When functioning correctly, the brain finds the sweet spot on the mood spectrum. But the sleep-deprived brain will swing to both extremes, neither of which is optimal for making wise decisions.” It’s thought that a fifth of adults suffer some form of sleep deprivation. It’s a common symptom of depression and other mental disorders. The Berkeley and Harvard researchers looked at the brains of healthy young adults. The pleasure circuits were boosted after a night of sleep deprivation, but it is the “same neural pathway that stimulates feelings of euphoria,” they say. Walker says people should not go without sleep – especially “people making high-stakes decisions.” He gives as examples airline pilots and people in the medical professions. “Based on this evidence, I’d be concerned by an emergency room doctor who’s been up for 20 hours straight making rational decisions about my health.” The euphoria is caused by a short-term boost in the levels of dopamine, a neurotransmitter that creates positive feelings. But it may lead people to feel overoptimistic, says Walker, and that can lead to impulsive decisions. The team’s findings are published in the Journal of Neuroscience. Reduced brain activity In 2009, Science News published details of imaging research – also in the Journal of Neuroscience – that showed why sleep deprivation affected some people more than others. Reduced brain activity was found in those people who were genetically vulnerable, but expanded brain activity was found in those who were more resistant. The article quoted Michael Chee, of the Duke–National University of Singapore Graduate Medical School as saying: “The extent to which individuals are affected by sleep deprivation varies, with some crashing out and others holding up well after a night without sleep.” A gene called PERIOD3 (PER3 for short) predicts how we respond to sleep deprivation, and we carry variants of this gene known as long and short. “Those with the short PER3 variant are resilient to sleep loss – they perform well on cognitive tasks after sleep deprivation. However, those with the long PER3 variant are vulnerable – they show deficits in cognitive performance after sleep deprivation,” says the 2009 article. Subjects were imaged while they performed tasks that needed cognitive control. Those with the long PER3 variant showed reduced activity in the brain structures that are usually associated with the task they were asked to do. Those with the short PER3 gene were found to create extra brain structures to compensate for lack of sleep.