Desynchronization of Human Circadian Rhythms

Abstract

In man as well as in animals, diurnal rhythms are based on endogenous, periodic processes which can be considered self-sustained oscillations in a technical sense2). Evidence for this is given by the observation that, underconstant conditions, the rhythm continues a) undamped and b) with a frequency which deviates from that of the earth's rotation6). It is this deviation of the free-running 'circadian '11) period from 24 hours which excludes external cues as possible causes of the rhythm. In many aspects, the whole organism behaves like a single oscillator which obeys the law of oscillation theory. Some findings, however, suggest that the circadian system consists of a multiplicity of oscillators which normally are synchronized with each other but which can become desynchronized under special circumstances13,14). Thishypothesis seems to be supported by recent results from experiments with human subjects which will be discussed below. METHODS Single subjects are kept in isolation and without watches in an underground soundproof bunker which is continuously illuminated. Next to the bed-sitting-room is a toilet and a small kitchen. The subject prepares his own meals. His rectal temperature is measured continuously by means of an electric thermometer and recorded outside the experimental chamber. The subject is asked to sample his urine in intervals of his own choice. The samples are stored in an ice box between the two lock-gates of the entrance from where they are removed for analysis. The subject can not perceive the time of removal. The records of several system of electric contacts, activated by the subject either consciously or unconsciously, serve to survey the subjects general activity. Communication between experimenter and subject is restricted to letters. Other details of the arrangements are given in two earlier publications4,8). RESULTS A subject who is kept in isolation and without a time-telling device con

The dependence of onset and duration of sleep on the circadian rhythm of rectal temperature

“…Fig. 5 in Aschoff et al 1967a). A similar dependence of temperature on the phase of the sleep-wake cycle has been observed in the 10 desynchronized subjects whose data are discussed here; details of the analysis are published elsewhere (Aschoff 1981b;Zulley and Wever 1982).…”

“…the rhythm of rectal temperature frequently show the same period of about 25 h and keep a stable phase-relationship to each other, a state which is called "internal synchronization". However, in about 30 % of such experiments the coupling between the two functions has been found to be instable, resulting in differen t frequencies of the two freerunning rhythms and, hence, in a continuous variation of the phase-relationship between the sleep-wake cycle and the rhythm of rectal temperature (Aschoff et al 1967a). In such a state of "internal desynchronization" the coupling forces, although insufficient for mutual synchronization, still exert an influence on both rhythms.…”

Development of the mouse circadian pacemaker: Independence from environmental cycles

“…Even so, it is possible, but unlikely, that in our experiments some aspect of circadian maternal rhythmicity was not entrained to the non-24-h cycles as was wheel-running activity. Although entrainment of the wheel-running activity rhythm was confirmed in all mothers, it has been found in primates (but not rodents) that different rhythms can have different limits of entrainment (Aschoff et al 1967;Sulzman et al 1978).…”

Interaction Between the Sleep-Wake Cycle and the Rhythm of Rectal Temperature

“…1. The oscillatory interaction, which leads to internal synchronization inside and to internal relative coordination outside the mutual ranges of entrainment (Aschoff et al 1967, Wever 1968). …”