The effect of real and simulated time‐zone shifts upon the circadian rhythms of body temperature, plasma 11‐hydroxycorticosteroids, and renal excretion in human subjects

Abstract

SUMMARY1. Observations were made upon five subjects who flew through 4j-6 time zones, four of them returning later to their starting point, and upon twenty-three subjects experiencing simulated 6 or 8 hr time zones shifts in either direction in an isolation unit.2. Measurements were made of plasma concentration of li-hydroxycorticosteroids, of body temperature, and of urinary excretion of sodium, potassium and chloride. Their rhythm was defined, where possible, by fitting a sine curve of period 24 hr to each separate 24-hr stretch of data and computing the acrophase, or maximum predicted by the sine curve.3. The adaptation of the plasma steroid rhythm was assessed by the presence of a sharp fall in concentration after the sample collected around 08.00 hr. The time course of adaptation varied widely between individuals; it was usually largely complete by the fourth day after westward, and rather later after eastward, flights. After time shift the pattern often corresponded neither to an adapted nor to an unadapted one, and in a subject followed for many months after a real flight a normal amplitude only appeared 2-3 months after flight.4. Temperature rhythm adapted by a movement of the acrophase, without change in amplitude, although on some days no rhythm could be observed. This movement was always substantial even on the first day, and was usually nearly complete by the fifth.5. High nocturnal excretion of electrolyte was often seen in the early days after time shift, more notably after simulated westward flights. Adaptation of urinary electrolyte rhythms usually proceeded as with temperature, but the movement of the acrophase was slower, more variable ANN L. ELLIOTT AND OTHERS between individuals, more erratic, and sometimes reversed after partial adaptation. On a few days there were two maxima corresponding to those expected on real and on experimental time.6. Sodium excretion was much less regular than that of potassium, but adapted more rapidly to time shift, so that the two often became completely dissociated. Chloride behaved much as sodium.7. The time course of adaptation of the plasma steroid and urinary potassium rhythms were sufficiently similar to suggest a causal connexion. The time course of adaptation of the temperature rhythm did not coincide with that of any other component considered here.

Irregularity of rest and activity: studies on circadian rhythmicity in man.

“…Such an effect has been reported after real or simulated time zone shifts (Elliott et al 1972;Aschoff, Hoffman, Pohl & Wever, 1975;Klein & Wegmann, 1979) and during shift work (Akerstedt & Froberg, 1975;Chaumont, Laporte, Nicolai & Reinberg, 1979;Vieux, Ghata, Laporte, Migraine, Nicolai & Reinberg, 1979). In all cases the loss of the normal phase relationship between rhythms may represent a true dissociation due to the different 290 IRREGULARITY OF REST AND ACTIVITY relative strengths of zeitgeber and internal component for each variable or an apparent one arising from the exogenous effects.…”

“…Eight experiments were carried out in an isolation unit (Elliott, Mills, Minors & Waterhouse, 1972) under constant conditions of temperature and humidity. In all cases, experimental days were preceded by a number of control days during which meals were eaten at conventional hours and sleep taken between 23.45 and 07.45 h ( Table 1).…”

The physiological rhythms of subjects living on a day of abnormal length.

“…In previous papers we have described the physiological rhythms of human subjects living in isolation, and either experiencing sudden simulated time-zone shifts (Elliott, Mills, Minors & Waterhouse, 1972) or deprived of knowledge of time (Mills, Minors & Waterhouse, 1974). We here report observations on subjects living on a 'day' of 21 or 27 hr.…”

Adaptation to abrupt time shifts of the oscillator(s) controlling human circadian rhythms.

“…Preliminary accounts of the method and results (Minors & Waterhouse, 1977;Minors, Mills & Waterhouse, 1977) have already appeared METHODS Thirty-six subjects, in groups of two to five, have been studied in the isolation unit described by Elliott, Mills, Minors & Waterhouse (1972), and one subject was studied alone on a second occasion. Initially subjects were studied for between 36 and 108 hr living on a customary nychthemeral routine.…”