When fatigue sets in over the course of a day, we all increasingly and unconsciously rely on emergency sources of energy: adrenalin, noradrenalin and cortisol. In this aroused fight-or-flight state, our prefrontal cortex, which helps us think reflectively and creatively, begins to shut down. We become more reactive, reflexive and impulsive. The pioneering sleep researcher Nathaniel Kleitman gave the name “basic rest activity cycle” to the 90-minute period at night during which we move through the five stages of sleep. A decade later, he reported that we experience a parallel 90-minute cycle in our waking lives. At night, we move from light to deep sleep and back out. During the day, we oscillate every 90 minutes from higher to lower alertness. In effect, our bodies are asking us for a break every 90 minutes. But we override the signals with coffee, sugar and our stress hormones.How can you translate that to your speaking? Be aware that if you're onstage or on the premises, but have to wait an hour to speak, you might well be at the end of your energy cycle rather than the top of it--and so will your audience. You might then need to avoid coffee, make sure you've fueled your body with protein right before you talk, and integrate some physical activity--taking your mic into the audience, getting them to stand up and move for a warm-up exercise, or some other tactic--to keep energy high. If you're helping to plan the agenda, keep that 90-minute cycle in mind when planning breaks. This hour-and-a-half cycle is just one more reason to be brief and energetic and find ways to get the audience physically and mentally engaged.
How do you manage your energy when you're speaking--or see to the energy needs of your audience?