Time of occurrence of cardiac death due to arrhythmia, heart failure, or acute myocardial infarction was recorded in 86 elderly subjects, belonging to a group in whom circadian and circannual rhythms in blood pressure and urinary catecholamine excretion had been studied previously. All patients were retired, with no work responsibilities, and lived--closely-supervised in a home for the aged--on a routine that provided little differences between weekdays and weekends. Cardiac mortality showed a circadian variation, with a peak in the early morning hours, coinciding with the circadian peak in systolic and diastolic blood pressures. A weekly (circaseptan) variation in cardiac mortality was found, with the greatest number of patients dying on Mondays and the least on Thursdays. There were seasonal differences in cardiac mortality, with a peak in July and a broader peak during the cold season (December to February). The former coincides with the circannual peak in diastolic blood pressure, but is unrelated to the seasonal variation in norepinephrine excretion. Circadian, circaseptan, and circannual variations in cardiac mortality appear to be the expression of time-dependent, transient risk states for catastrophic cardiac events, which may lend themselves to preventive treatment.

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Clinically significant fatigue is common among patients with COPD and is associated with an increased disease burden. It should therefore be integrated as a measure of disease prognosis and control in patients with COPD.

The circadian rhythms in blood hormone concentrations of 17 pituitary, adrenal, pancreatic, testicular, and thyroid hormones were determined in 9 women and 5 men 81 to 91 years of age. Six samples over a 24-hr span were studied for each hormone. Even with the small sample available, 9 of the 17 hormones determined showed a statistically significant circadian rhythm as a group phenomenon (prolactin, estradiol, 17-hydroxyprogesterone, insulin, C-peptide, thyroid stimulating hormone, aldosterone, cortisol, dehydroepiandrosterone sulfate). No rhythm detection by population mean cosinor analysis at the .05 level was obtained in this relatively small group of subjects for adrenocorticotropic hormone, follicle stimulating hormone, growth hormone, luteinizing hormone, triiodothyronine, thyroxine, progesterone (determined in women only) and testosterone (determined in men only).

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