> Fu, a geneticist, analyzed their DNA and found one particular mutation in a gene known to regulate circadian rhythms that seemed to separate them from their s

> Fu, a geneticist, analyzed their DNA and found one particular mutation in a gene known to regulate circadian rhythms that seemed to separate them from their sleep-deprived counterparts. She then inserted that mutation into mice genomes.The effect was clear: the animals with the mutation not only began to sleep less than their counterparts but continued functioning well even after six hours of sleep deprivation (a long time for a mouse). Those without the mutation showed the usual signs of deprivation. This is pretty cool as it means that at least some aspects of sleep deprivation are caused by dedicated circuitry. It's basically like pain, your body is doing it to yourself.