The occurrence of circadian rhythm in respiration in healthy persons and in patients with bronchial asthma

The authors examined in 69 healthy young men at times 0, 3, 6, 9, 12, 15, 18 and 21 hours values of FVC, FEV1, FEF50 a PEF. In 149 patients with bronchial asthma after the same time intervals FEV1 was assessed, whereby the interval at 3 a.m. was used as the mean of values at times 0 and 6 a.m. By analysis of variance the minima of the majority of investigated indicators were assessed in healthy subjects at 3 a.m. and 9 a.m. By cosinor analysis a statistically insignificant circadian rhythm for values FEC and FEV1 was proved in the entire group of healthy subjects and in subgroups of smokers and non-smokers. No rhythm was found in values of FEF50 and PEF. Rhythms in the ventilation values were detected in 40-60% of the subjects, in the remainder no rhythms were detected. In patients with bronchial asthma a significant circadian rhythm of FEV1 changes was found in groups with a morning or variable type of respiration. In groups with a stabilized ventilation a rhythm was detected but was not significant. In the group with an apparently irreversible obstruction no circadian rhythm was found.