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freerunning in humans

Roxanne Sterniczuk, Richard H Dyck, Frank M Laferla, Michael C Antle
Circadian disturbances, including a fragmented sleep-wake pattern and sundowning, are commonly reported early in the progression of Alzheimer's disease (AD). These changes are distinctly different from those observed in non-pathological aging. Transgenic models of AD are a promising tool in understanding the underlying mechanisms and cause of disease. A novel triple-transgenic model of AD, 3xTg-AD, is the only model to exhibit both Abeta and tau pathology, and mimic human AD. The present study characterized changes pertaining to circadian rhythmicity that occur prior to and post-AD pathology...
August 12, 2010: Brain Research
R S Pandian
The crepuscular biting rhythm of A. subalbatus has been found to be a genuine circadian rhythm. When the entrained biting rhythm is allowed to freerun in constant darkness (DD) and continuous illumination (LL), it persists in DD (tau = 24.36 hr) and also in LL of ca. 0.1 1x (tau-23.82 hr) thus deviating from the strict 24 hr periodicity of the geophysical day. The biting rhythm becomes arrhythmic in LL of 1.0, 10, 0.4, 4, 40 lx even the first cycle damping away.
April 1994: Indian Journal of Experimental Biology
J Zulley, R Wever, J Aschoff
The sleep-wake cycle and the circadian rhythm of rectal temperature were recorded in subjects who lived singly in an isolation unit. In 10 subjects, the freerunning rhythms remained internally synchronized, 10 other subjects showed internal desynchronization. Times of onset and end of bedrest ("sleep") were determined in each cycle and referred to the phase of the temperature rhythm. In the synchronized subjects, onset of sleep occurred, on the average, 1.34 h before the minimum of temperature, and end of sleep 6...
October 1981: Pflügers Archiv: European Journal of Physiology
R A Wever
Under the influence of artificial zeitgebers, human circadian rhythms can be entrained only within limited ranges of periods; different overt rhythms may show different entrainment limits. When the period of a zeitgeber is varied slowly but continuously, entrainment limits can be evaluated precisely. An overt rhythm is synchronized to the zeitgeber only up to a certain day, or period respectively, until it breaks away from the zeitgeber and starts to freerun. The interindividual comparison among different subjects shows that the range of entrainment is positioned nearly symmetrically around the freerunning period...
February 1983: Pflügers Archiv: European Journal of Physiology
Y Chiba
In a 950-day observation, a school- refuser showed a freerunning circadian rest-activity rhythm of 24.5 h interrupted intermittently by days of irregular rest-activity cycle. The interruption may be explained by an interaction between two desynchronized rhythmic components; one is freerunning and the other is of 24.0 h. The symptoms of emotional disorder were observed more frequently during days of interruption.
January 1984: Chronobiologia
R A Wever
The period of freerunning circadian rhythms is significantly shorter and the fraction of sleep is significantly larger in human females than in males, as long as the rhythms run internally synchronized. The sex difference in the period could be a property either of the whole circadian system or of only one of the oscillators in a multi-oscillator system. The sex difference in the sleep fraction could be a fixed property of the sleep-wake rhythm or could depend on interactions in the multi-oscillator system...
November 15, 1984: Experientia
A Wirz-Justice, R A Wever, J Aschoff
Retrospective analysis of data collected over 15 years in normal subjects isolated from time cures showed seasonal rhythms in the circadian period of the core temperature rhythm, in the amount of sleep (both shorter in spring and longer in autumn), and in the incidence of internal desynchronisation (most often in summer). Women slept longer than men at all times of year.
June 1984: Die Naturwissenschaften
R A Wever
Circadian rhythms are of endogenous origin, in humans as in all organisms. Under temporal isolation, i.e., after exclusion of all environmental time cues, circadian rhythmicity persists but with a period slightly deviating from 24 hours; in human, freerunning circadian rhythms always show periods close to 25 hours. In a minority of experiments, overt rhythms of different variables do not run in mutual synchrony but internally desynchronized in the steady state. This means that, indeed, most physiological rhythms, and particularly that of body temperature, hold a period close to 25 hours; it is mainly the sleep-wake rhythm (but also the overt rhythms of several more variables) which shows freerunning periods being considerably longer or shorter than 25 hours...
1986: Journal of Neural Transmission. Supplementum
J Aschoff
The circadian system of man consists of a multiplicity of self-sustaining oscillators which are coupled to each other and which can be entrained by periodic factors in the environment, the zeitebers. From the interaction of these two forces results a high degree of temporal order within the organism. Freerunning circadian rhythms to be observed in isolated subjects living in constant conditions, usually have periods close to 25 h. The circadian system can split into components that freerun with different frequencies (internal desynchronization) and that partially can be entrained by zeitgeber...
1978: Arzneimittel-Forschung
R A Wever
While living under constant conditions and complete isolation from environmental time cues for about 4 weeks, 9 male subjects exercised on a bicycle ergometer seven times per 'day' during two weeks and refrained from physical activities during the other 2 weeks. The freerunning circadian rhythms of wakefulness and sleep and of rectal temperature showed, on the average, no difference between the two sections with regard to the autonomous period and the tendency towards internal desynchronization. Even in the one experiment in which the two rhythms became internally desynchronized, the periods of the rhythms remained unchanged during the time the subject worked on the bicycle...
August 1979: Pflügers Archiv: European Journal of Physiology
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