Why do some people exceed expectations at work with seemingly little effort, while others struggle just to get through their workload? Maybe the Fred Astaires among us intuitively work with their bodies instead of against them.Working with your body’s natural rhythms is something that the folks at Asian Efficiency, a productivity training company” teach people to do, based on the work of sleep researcher Nathaniel Kleitman and later performance psychologist Jim Loeher. In the 1950s, Kleitman discovered that humans have daytime cycles (rest-activity cycles) as well as sleep cycles. He found we work best and are most productive and effective when we engage in a task single-mindedly for 90-120 minutes, and follow this by a period of rest, from 20-30 minutes. Fifty years later, Jim Loeher with business writer Tony Schwartz published their best-seller, The Power of Full Engagement: Managing Energy, Not Time, is the Key to High Performance and Personal Renewal, an energy-m…