In a recent article for the New Yorker, neuroscientist Kenneth Wright said that “cognition is best several hours prior to habitual sleep time, and worst near habitual wake time”—which suggests that you do your best work later in the day, not first thing in the morning. Your consciousness kicks in almost immediately after waking up, but it can take up to four hours for your mind to crank itself up to full awareness and alertness—and in that time, you won’t make good decisions.

So how do employers accommodate this?

A shorter workday works particularly well for knowledge workers—people in creative or professional jobs—who can work productively for about six hours a day, compared to the eight hours manual laborers can churn out, according to Salon. Unlike machines, humans operate on a cyclical basis, which means our energy and motivation fluctuate in peaks and troughs. Cognitive workers tend to be more focused in the late morning, getting another energy boost in the late afternoon when lung efficiency peaks.