Maria Konnikovan – the author of the rather good Mastermind: How to Think Like Sherlock Holmes – has written an article for the New Yorker which looks at the challenges of having our sleep regulated by actual clocks rather than our body clock. It includes some rather startling facts about just how dangerous this can be:
Roenneberg and the psychologist Marc Wittmann have found that the chronic mismatch between biological and social sleep time comes at a high cost: alcohol, cigarette, and caffeine use increase—and each hour of social jetlag correlates with a roughly thirty-three per cent greater chance of obesity. “The practice of going to sleep and waking up at ‘unnatural’ times,” Roenneberg says, “could be the most prevalent high-risk behaviour in modern society.” According to Roenneberg, poor sleep timing stresses our system so much that it is one the reasons that night-shift workers often suffer higher-than-normal rates of cancer, potentially fatal heart conditions, and other chronic disease, like metabolic syndrome and diabetes. Another study, published earlier this year and focussing on medical-school performance, found that sleep timing, more than length or quality, affected how well students performed in class and on their preclinical board exams. It didn’t really matter how long they had slept or whether they saw themselves as morning people or not; what made a difference was when they actually went to bed—and when they woke up. It’s bad to sleep too little; it’s also bad, and maybe even worse, to wake up when it’s dark.