I have long harboured a secret resentment against morning people. While I bash the snooze button for the umpteenth time they are exercising and catching up on emails. Studies have shown that such early birds are happy and healthier—and even make more money.

Yet when I try to emulate them I find myself staring blankly at my screen for most of the day. It turns out that our circadian rhythms are largely a product of our genes, which is why buying a sunlight alarm clock hasn’t helped me much.

Waking up early is not all upside. Research shows that night owls have more sex, for example. But chances are that, like me and most other people, you are neither an early bird nor a night owl, but someone who is in between. That is, after all, why the work day is from nine to five.