XVI. Circadian Rhythm Influences on Medical Conditions, and Risk Factors

While our literature survey has emphasized circadian factors that affect psychological and sleep disturbances, and non-drug treatment approaches that normalize the daily cycle, there is an explosion of research on medical applications that very possibly will transform how doctors diagnose illness and manage treatment, with less reliance on conventional medication, or with significant dose reduction and minimization of adverse effects.  Again, it boils down to determination of the effects of disrupted or displaced circadian rhythms as a major pathogenic agent.

The immune system itself is modulated by the inner clock, and is compromised when clockwork goes awry. Cancer cells proliferate on a circadian cycle, and interventions can be optimized with appropriately timed treatment. Circadian misalignment is a distinct precursor to diabetes.  The list goes on and on, as you will see by checking (and reading) our references.

Our underlying message is that the armamentarium of chronotherapy—light therapy, light protection, wake therapy, melatonin administration (all of these time-anchored to an individual’s chronotype, rather than the clock on the wall)—is in the cards for supplementation or even substitution for conventional medical therapeutics.



  • Turek F, Zee P (eds.).  Regulation of Sleep and Circadian Rhythms. Boca Raton, Florida, CRC Press, 1999
  • Smolensky M, Lamberg L. The Body Clock Guide to Better Health: How to Use your Body’s Natural Clock to Fight Illness and Achieve Maximum Health. New York, Holt, 2001