Seasonal rhythms of energy metabolism

Seasonal rhythms and exercise.

Levels of leisure-time physical activity and physical fitness are generally higher in the summer than in the winter months for most people living away from the equator. The notion that an abrupt increase in physical activity in the spring, after a period of relative inactivity, can trigger sudden cardiac events has not been confirmed. There are seasonal variations in the physiological responses...

Mammalian Seasonal Rhythms: Behavior and Neuroendocrine Substrates

“Environmental seasonality. . . a basic component of the ecosystem within which our ancestors evolved. . . left its mark indelibly upon the makeup of our biology and our behaviour.” ( Johnston, 1993) “the ability to perceive changes in daylength indicated by changes in the duration of melatonin secretion. . . is the only essential function attributable to melatonin in mammals to date.” (Arendt,...

Editorial: Circadian Rhythms and Metabolism

Circadian rhythms, sleep, and metabolism.

The discovery of the genetic basis for circadian rhythms has expanded our knowledge of the temporal organization of behavior and physiology. The observations that the circadian gene network is present in most living organisms from eubacteria to humans, that most cells and tissues express autonomous clocks, and that disruption of clock genes results in metabolic dysregulation have revealed inter...

Metabolism and the control of circadian rhythms.

The core apparatus that regulates circadian rhythm has been extensively studied over the past five years. A looming question remains, however, regarding how this apparatus is adjusted to maintain coordination between physiology and the changing environment. The diversity of stimuli and input pathways that gain access to the circadian clock are summarized. Cellular metabolic states could serve t...