Allochronism versus dyschronism There is evidence of interest in human biological rhythms and their implications for health and disease in ancient Chinese cultures, since the time of the mythical

emperor Chennong (3000 to 4000 years ago). Sickness was related to an alteration of the yin-yang cycles, ie, when they are not in harmony with those of the universe.47 In 1797, Lavoisier and Seguin74 were the first to report a rhythm of “about 24 h” in human body weight. They were so impressed by the regularity of this cyclic phenomenon that they suggested an association of circadian rhythm Inhibitors,research,lifescience,medical alterations with states of pain and disease. However, the question of how to handle our biological rhythms to live

Inhibitors,research,lifescience,medical to a ripe old age and in good health remains unanswered.75 As stated in the introduction, the stable structure of temporal order is highly advantageous for the organism. We have also presented evidence63-73 that desynchonizatlon of a set of human circadian rhythms is rather frequent. Does this mean that a subject with an alteration of temporal organization is a sick (or potentially a sick) person? In the late 1970s, the answer to this question Inhibitors,research,lifescience,medical would have been “yes” because the prevailing assumption at that time was that irregularity in a rhythm and/or changes in the temporal organization corresponded Inhibitors,research,lifescience,medical to a pathological state, or at least to “… a statistically significant learn more higher (P<0.05) chance of progression toward overt disease.”76 The values of the computed rhythm parameters were averaged from population studies without focusing on interindividual variability. Dyschronism, a term coined by Halberg et al76 was defined as a “time

structure (including rhythm) alteration associated with demonstrable physical, physiological, or mental deficit, if not disease.” The definition also states: “Dyschronism is not necessarily a determinant of overt or occult disease.” To illustrate this definition, Inhibitors,research,lifescience,medical one can regard the clinical intolerance to shift work as dyschronism, from the point of view of medical chronobiology.77, 78 Intolerance to shift work was defined by the following symptoms63, 78, 79: Sleep alterations, like poor sleep quality, difficulty falling asleep Electron transport chain when retiring, frequent awakenings. Persistent fatigue that does not disappear after sleep, weekends, days off, and vacations. Changes in behavior, consisting of unusual irritability, tantrums, malaise, and feeling of inadequate performance. Digestive problems (which seem to be less frequent than 20 years ago). The regular use of sleeping pills (barbiturates, benzodiazepines, phenothiazines, tranquillizers, antidepressants, etc), especially when sleep cannot be controlled or even improved by these medications or others.