Day sleep (after night work) and night sleep (after day work) were studied in two groups of locomotive engineers aged 25-35 and 50-60 a, respectively. All recordings were made in the homes of the subjects. For both groups day sleep was reduced by approximately 3.3 h, mainly affecting rapid eye movement sleep and stage 2 sleep. Diuresis and the excretion of noradrenaline were increased during day sleep. The ratings of sleepiness were higher after night work than after day work. Several indices of disturbed daytime sleep correlated significantly with catecholamine excretion. The age groups differed mainly in that the older subjects had relatively more stage shifts, awakenings, stage 1 sleep, a higher diuresis, and a higher noradrenaline excretion during day sleep. It was concluded that night work is detrimental to sleep and that negative effects are exacerbated by increasing age.
Many patients with obstructive sleep apnea (OSA), but not all, have a reduction in blood pressure (BP) with positive airway pressure (PAP) treatment. Our objective was to determine whether the BP response following PAP treatment is related to obesity. A total of 188 adults with OSA underwent 24-hour BP monitoring and 24-hour urinary norepinephrine collection at baseline. Obesity was assessed by waist circumference, body mass index, and abdominal visceral fat volume. Participants adherent to PAP treatment were reassessed after 4 months. Primary outcomes were 24-hour mean arterial pressure (MAP) and 24-hour urinary norepinephrine level. Obstructive sleep apnea participants had a significant reduction in 24-hour MAP following PAP treatment (-1.22 [95% CI: -2.38, -0.06] mm Hg; P = .039). No significant correlations were present with any of the 3 obesity measures for BP or urinary norepinephrine measures at baseline in all OSA participants or for changes in BP measures in participants adherent to PAP treatment. Changes in BP measures following treatment were not correlated with baseline or change in urinary norepinephrine. Similar results were obtained when BP or urinary norepinephrine measures were compared between participants dichotomized using the sex-specific median of each obesity measure. Greater reductions in urinary norepinephrine were correlated with higher waist circumference (rho = -0.21, P = .037), with a greater decrease from baseline in obese compared to non-obese participants (-6.26 [-8.82, -3.69] vs -2.14 [-4.63, 0.35] ng/mg creatinine; P = .027). The results indicate that the BP response to PAP treatment in adults with OSA is not related to obesity or urinary norepinephrine levels.
Metabolic and hormonal variations of crewmembers of MI-6 and MI-8 helicopters were investigated. The investigation was performed on 61 pilots, including 18 in the hot and 43 in the cold climate. The following parameters were measured before and after flight: nonesterified fatty acids, lactic acid, insulin, and cortisol in blood, and catecholamines and cortisol in urine. In the hot climate the content of nonesterified fatty acids, lactic acid and insulin increased. The renal excretion of catecholamines and cortisol grew drastically. In the cold climate nonesterified fatty acids increased postflight. Insulin, catecholamines and cortisol tended to grow.
This study examined the hormonal and thermal responses of two groups of subjects during 16 days in the Arctic (mean temperature -26.8 degrees C). One group (NPA) received no prior cold exposure, whereas the second group (PA) was subjected to nine daily immersions (20-40 min) in cold water (15 degrees C) 20 days before the Arctic exposure. Nude cold tolerance tests (cold air at 10 degrees C) were administered to both groups before and after the Arctic exposure. The NPA group showed an increase in metabolism and rectal temperature, whereas the PA group showed no elevation in metabolism and a decrease in rectal temperature. In the Arctic significant daily increases over the control period of urine volume (+86%), urinary norepinephrine (+48%), epinephrine (+84%), and 17-hydroxycorticosteroids (+34%) occurred in the NPA group. Only epinephrine (+65%) increased in the PA group. The hormonal and thermal responses of the NPA group in the Arctic were characteristic of metabolic adaption, whereas those in the PA group were suggestive of a hypothermic type of adaptation or habituation with no evidence of sympathetic or adrenocortical stimulation. The hormonal and thermal responses observed in this study indicate that a degree of cold resistance can be induced rapidly in humans by short intermittent exposures to an intense cold stress, which persists for a significant period of time after the last exposure.