Circadian Synchrony and Optimal Physiological Function

How core body temperature rhythm and synchrony affect peak stamina

Everywhere you look within human physiology, timing within each daily 24 hour cycle, and coordination with related processes are both critical to optimal function. When timing and coordination are aligned, circadian synchrony and wellness are the results.

Examples of how circadian synchrony contributes to health and wellness are plentiful. Stamina is a good case in point. Peak stamina normally occurs in the late afternoon or early evening depending on time of year and geolocation. Peak stamina also occurs around the same time as when core body temperature peaks in the late afternoon or early evening.

The core body temperature peak occurs because blood flow to the skin is decreased which reduces heat loss by convection to the air and more heat retention in the core. This how the body produces the core temperature peak. The reason peak core temperature and decreased skin blood flow optimize stamina is that the heart doesn’t need to work as hard to cool the body so more of its work can go to supplying oxygen and energy to muscles.

It might seem surprising that a reduction in cardiac work due to a reduction in skin blood flow could improve stamina. This relationship makes sense when you realize the increased skin blood flow that occurs when the core is too warm can increase the demand on the heart by up to 60%. So if you exercise in the morning when the core temperature is cooler, your heart will have to work harder for the same amount of exercise because your heart will have to send more blood to the skin to meet the core body’s demand to be cooler.

The inter-relation of these coordinated physiological processes can seem complicated. The good thing is you don’t need to be a physiologist to understand how to use circadian synchrony to optimize stamina. There will be more information on this in future articles; for now the key point is regular, sufficient sleep and morning bright light support a strong melatonin cycle, which in turn support a robust core body temperature cycle and peak stamina.  

Dynamic Daily and Seasonal Cycles of Sunlight
The Survival Value of Predictive Adaptation
Circadian Synchrony and Optimal Physiological Function
New Approaches to Wellness and Treatment
Integrating Circadian Synchrony with Contemporary Life
Afternoon Tips for Circadian Synchrony
Integrating Circadian Synchrony at Night
American Society for Photobiology
CIrcadian Rhythm
Healthfinder Sleep Resources
International Dark Sky Association
Kavli Institute conference: Biological Switches and Clocks
National Sleep Foundation
Sleep Research Society