CJA
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Full Text (PDF)
Right arrow Submit a scholarly reply
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by HUNTER, M. E.
Right arrow Search for Related Content
PubMed
Right arrow Articles by HUNTER, M. E.

Canadian Journal of Anesthesia, Vol 16, 253-259, Copyright © 1969 by Canadian Anesthesiologists' Society

Circadian Rhythms and their Significance to the Anaesthetist: A Review

MARY E. HUNTER M.D., C.M., F.R.C.P.(C)1

1 Department of Anaesthesia, Toronto General Hospital, Toronto, Ontario

Many functions show a circadian rhythm, and it has recently been shown that this natural rhythm is of great practical importance, especially if we attempt to understand why mortality should vary so greatly at different times of the day from various causes and why we are aware of certain phenomena occurring when we are deprived of a natural periodicity in our day. There is certainly a circadian biological "clock," and it may with fair certainty be placed in the region of the hypothalamus. There is no real evidence that more than one such "clock" exists, but it is quite within the realm of possibility that endogenous rhythms may occur at many different levels of physiological organization. Some of the circadian rhythmicity must be merely impressed on the receptive region by habit, sensory deprivation, environment and social contact, and the function of light and darkness; other circadian influences - Zeitgeber - must only adjust the timing, as circadian rhythm occurs quite naturally in animals that have never been exposed to any known rhythm. It is the hypothalamic region that apparently triggers these rhythms. How this region may be stimulated by a signal from the eye, or from the region of the eye, is unknown; but it is certainly the hypothalamus which thus activates the pituitary, which in turn regulates the adrenal cortex, the thyroid, the reproductive organs, and so the entire endocrine and metabolic systems which keep us all "turning over" in a circadian rhythm. Thus, when we come to understand how outside pathological and even iatrogenic influences can disrupt this intrinsic normal biological pattern (which may or may not be measured in quantitative terms) we should no longer be surprised to find basic dislocations occurring in the integrity of the organism, and we should be able to predict how they may alter the patient's progress.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1969 by the Canadian Anesthesiologists' Society.