In search of a biological hour

• Published in: Journal of plant physiology Vol. 151; no. 3; pp. 352 - 357
• Main Authors: Koukkari, Willard L., Bingham, Christopher, Hobbs, Johnna D., Duke, Stanley H.
• Format: Journal Article
• Language: English
• Published: Jena Elsevier GmbH 1997; Elsevier
• Subjects: Biological and medical sciences; Chronobiology; circumnutation; Fundamental and applied biological sciences. Psychology; Movements; Phaseolus vulgaris L; Plant physiology and development; REM sleep; stress; ultradian rhythms; Vertebrates: anatomy and physiology, studies on body, several organs or systems; stress; non-REM; Exps; ultradian rhythms; circumnutation; REM; Exp; Phaseolus vulgaris L; REM sleep; Human; Irregularity; Periodicity; Environmental factor; Biological rhythm; Wobble; Stress; Bean; Sleep; Leguminosae; Phaseolus vulgaris; Dicotyledones; Ultradian rhythm; Angiospermae; Spermatophyta
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/S0176-1617(97)80264-7

We focus here on a prominent subset of rhythms within the ultradian domain that have periods between 30 and 240 min as a candidate for a «biological hour.» Smooth histograms produced from reported periods obtained from two surveys of literature display prominent peaks centered near 95 min, with a range from about 50 to 130 min. The list of variables having these periodicities is extensive and diverse (e.g., circumnutation movements of plants and the REM/non-REM sleep cycle of human beings). The periodicity displayed by many of these examples is somewhat irregular, perhaps because of other changing biological components and/or environmental factors such as stress. For example, results from our experiments showed that when
Phaseolm vulgaris L. shoots were subjected to stress caused by staking, the ultradian periodicity of circumnutation was initially lengthened and later restored to its «normal» length.