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Biomedical subjects

J E Fröberg

Publications and source records attributed to J E Fröberg.

6 recordsLinked to original sources
PubMed1981

Circadian variations in cardiovascular parameters during sleep deprivation. A noninvasive study of young healthy men.

Twelve subjects were kept awake for 64 h under conditions of isolation from external time cues. Activity was sedentary and kept as constant as possible over time, as was intake of food and drink. Cardiovascular variables--blood pressure, heart rate, contractility (IJ-amplitude from ballistocardiogram), T-wave amplitude, QRS, PQ and QT intervals--were assessed every 3 h. At the same intervals, urine samples for catecholamine analysis were obtained. Data were analyzed by analysis of variance and cosinor techniques. Adrenaline excretion showed a pronounced circadian rhythm. Noradrenaline excretion and IJ amplitude showed much weaker rhythmicity, statistically significant only with the cosinor technique. The remaining variables showed no rhythmicity with either technique. It was concluded that constant conditions (including sleep deprivation) markedly disturb or even obliterate the circadian rhythms of cardiovascular variables and urinary noradrenaline excretion. It was also concluded that most of the amplitude of cardiovascular circadian rhythms measured under habitual sleep/wake conditions must be due to the alternation between sleeping and waking. The present data do not, however, rule out the existence of selfsustained circadian rhythmicity in cardiovascular variables; a design including continuous wakefulness may well have concealed endogenous low-amplitude rhythms.

Adult↗
PubMed1979

Sleep and stressor exposure in relation to circadian rhythms in catecholamine excretion.

12 healthy male volunteers spent 64 h of continuous waking under strictly controlled environmental conditions (light, food, drink, activity) in isolation from the external world. Before and after the vigil the subjects slept in the laboratory. An additional group of five participated only during day time and spent the intervening night period asleep at home. Measurements were carried out in 3 h intervals except for sleep periods. Shortly before the circadian trough and peak of adrenaline excretion respectively, the subjects were exposed to a performance stressor. Results from the vigil showed a very pronounced circadian rhythm for adrenaline excretion but none for noradrenaline excretion. For adrenaline, night-time sleep reduced excretion levels, causing an even more pronounced circadian pattern. For noradrenaline, night-time sleep caused a drop in excretion giving the impression of a circadian rhythm. These and previous results led to the conclusion that the excretion of adrenaline exhibits a self-sustained rhythm while a rhythm in noradrenaline excretion is found only when caused by external synchronizers such as sleep-wake alternation. No difference in magnitude of stress response between peak and trough was observed for any of the catecholamines. Night-time (trough) exposure completely obliterated the circadian rhythm of adrenaline excretion for the duration of the exposure. It was concluded that the normal pronounced night-time trough of adrenaline cannot be due to unavailability of adrenaline in the medulla. With respect to sleep deprivation, no effect was found on excretion levels during waking, during sleep, or in response to the stressor as deprivation progressed. Finally, there was also found to be a close temporal covariation between adrenaline excretion and both rectal temperature and self-rated fatigue (neg.).

Adult↗
PubMed1977

Twenty-four-hour patterns in human performance, subjective and physiological variables and differences between morning and evening active subjects.

A study was undertaken to investigate differences between habitually morning active and evening active subjects as regards 24-hr patterns in physiological and subjective arousal and performance efficiency under conditions of 72 hr of sleep deprivation. The results were that very consistent 24-hr rhythmic were present in some of the performance variables, subjective alertness, oral temperature and urinary adrenaline excretion. No significant differences in 24-hr patterns could be detected between a group of habitually morning active and a group of evening active subjects. Significant correlations were obtained between oral temperature and some of the performance measures, while adrenaline excretion was not significantly correlated with performance. There were rather high correlations between subjective alertness ratings and some of the performances.

Adult↗
PubMed1976

Interindividual differences in circadian patterns of catecholamine excretion, body temperature, performance, and subjective arousal.

Interindividual differences in circadian rhythms of urinary catecholamine excretion, performance, self-ratings of arousal and oral temperature were studied in 80 subjects divided into three groups--morning-active, evening-active, and intermediate. Catecholamine excretion, body temperature, and self-ratings of arousal exhibited pronounced circadian variations. Morning-active subjects exceeded other groups in the 24 h level of adrenaline excretion but crest phases did not differ, occurring close to 13.00 h. No differences between groups were found for noradrenaline excretion. Crest phases occurred close to noon. Self-rated alertness exhibited a significantly earlier (14.12 h) crest phase for morning-active than for evening-active subjects (16.09 h). The performance did not differ between groups.

Arousal↗
PubMed1975

Circadian rhythms of catecholamine excretion, shooting range performance and self-ratings of fatigue during sleep deprivation.

Circadian rhythms in urinary catecholamine excretion, performance and self-ratings were studied in two experiments with a total of 29 subjects who were deprived of sleep for 72 hr. Adrenaline excretion and fatigue ratings showed the most consistent circadian variations; noradrenaline and performance rhythms were more irregular. The average crest phase for adrenaline excretion was around 1400 hr, for noradrenaline about 0800 hr, for performance 1700 hr and for fatigue 0500 hr. Twenty-four hour levels of performance and 'subjective arousal' decreased over the three days of sleep deprivation, while adrenaline excretion levels increased.

Adult↗