The acute effects of experimental short-term evening and night shifts on human circadian rhythm: the oral temperature, heart rate, serum cortisol and urinary catecholamines levels

Abstract

This study was designed to examine the temporal changes in circadian rhythm of oral temperature, heart rate, serum cortisol and urinary catecholamines levels due to experimental short-term shifts. The six subjects were assigned to consecutive day (work 0800-1600 hours; sleep 0000-0800 hours), evening (1600-2400 hours; 0400-1200 hours), and night (0000-0800 hours; 1200-2000 hours) shifts of 2 days each scheduled as hospital shiftwork by nurses, in random order, during which data were collected every 4 h throughout the experimental periods. According to acrophases of a fitted cosine curve and visual inspection on chronograms, the phases of circadian rhythms were delayed to different degrees in the evening shifts with a minimum of about 1 h for oral temperature and a maximum of about 4 h for urinary free noradrenaline. The corresponding phase delays were larger in the night shift for oral temperature (about 3 h), resting heart rate (about 5 h) and urinary free noradrenaline (about 13 h); the diurnal variations of serum cortisol and urinary free adrenaline were greatly modified, and their circadian rhythmicities disappeared, indicating that the normal circadian phase relations of these variables were disrupted more by the night shift. The comparison of chronograms and correlation analyses revealed that the 4-h mean heart rate and urinary free noradrenaline were largely affected by rest-activity level in connection with shifts, while the resting heart rate and urinary free adrenaline were less affected. On the other hand, the sleep factor (time of onset and/or period) seemed to be more potent in modifying the circadian rhythm of serum cortisol, especially with the night shifts.

Effects of Night Work on Urinary Excretion Rates of 6-Sulfatoxymelatonin, Norepinephrine and Estriol in Pregnant Women.

“…This was observed in both the pregnant and the non-pregnant subjects. These results do not contradict the physiological profile of normal NE secretion [10][11][12] . Urinary NE levels on the night work, however, were significantly increased in both the pregnant and the non-pregnant subjects, and the evident day/ night differences mentioned above were disappeared.…”

“…Thus, the urinary NE excretion rates of nighttime were significantly affected by the work shifts in both the pregnant and the nonpregnant subjects. Night work generally raises the NE level to flatten the physiological rhythm of NE secretion [10][11][12] . The results by ANOVA in this study indicated that this applies not only to non-pregnant but also to pregnant subjects.…”

“…Plasma NE concentration shows a tendency to be high during the daytime when one is in activity and low during the night when one is at rest. These characteristics of NE have lead investigators to use NE as an indicator of physical fatigue or stress [10][11][12] . Estriol, the major urinary estrogen, is produced in the placenta and mainly is of fetal origin.…”

Shiftwork and Diurnal Salivary Cortisol Patterns Among Police Officers

“…34–38 Cortisol, one of the primary stress hormones in man, has a well-documented circadian pattern which is established in infancy. 39–41 Light is a powerful synchronizer of the circadian rhythms and the external light–dark cycle synchronizes the central oscillator in the hypothalamus.…”

Physiological Response as Biomarkers of Adverse Effects of the Psychosocial Work Environment

“…Six studies found a positive association of catecholamines with organisational factors; two associated monotony and high work pace to catecholamines (Lundberg et al, 1989;Timio et al, 1979) where four studies found a positive association between catecholamines and having shift work (Fujiwara et al, 2004;Fujiwara et al, 1992;Levitt & Derrick, 1991;Mulders et al, 1982). Positive associations with HbA 1C were found for both having shift work (Cesana et al, 1985) and organizational changes where the participants rated their psychosocial working environment poorer at follow-up (Netterstrøm & Hansen, 2000).…”