But during the day we assume that the brain is different. It’s as though we can readily accept this lovely oscillation at night, but in the morning we think we can just flick on the switch and the brain will be on GO all day. This is not so.
In a wonderful book called The Power of Full Engagement, authors Jim Loehr and Tony Schwartz discuss data that indicate our brains continue their 90-minute cycles throughout the day. Of course we aren’t in delta wave sleep during the day, but our brains are not simply in one phase all day long without variation. These authors’ overall point is that, by taking advantage of the natural variations in our alertness, we can become more resilient and reserve more energy. As we understand and work with these 90-minute cycles during daylight hours, we will not only work better during the day but sleep better at night, in part because we are calmer overall.