Chronic insomnia is associated with a shift of interleukin-6 and tumor necrosis factor secretion from nighttime to daytime

Chronic insomnia, by far the most commonly encountered sleep disorder in medical practice, is characterized by difficulty falling or staying asleep at night and increased fatigue during the day. Interleukin-6 (IL-6) and tumor necrosis factor (TNF) are fatigue-inducing cytokines, and the daytime secretion of IL-6 is negatively influenced by the quantity and quality of the previous night's sleep. We hypothesize that the poor quality of insomniacs' sleep is associated with a hypersecretion of these 2 cytokines during the daytime, which, in turn, correlates with the fatigue experienced by these patients. Eleven young insomniacs (6 men and 5 women) and 11 (8 men and 3 women) age- and body mass index (BMI)-matched healthy controls participated in the study. Subjects were recorded in the sleep laboratory for 4 consecutive nights and serial 24-hour plasma measures of IL-6 and TNF were obtained during the 4th day. Insomniacs compared to controls slept poorly (sleep latency and wake were increased, whereas percentage sleep time was decreased during baseline nights, all P <.05). The mean 24-hour IL-6 and TNF secretions were not different between insomniacs and controls. However, the difference in the change (increase) of IL-6 plasma levels from midafternoon (2 PM) to evening (9 PM) between insomniacs and controls was significant (P <.01). Furthermore, cosinor analysis showed a significant shift of the major peak of IL-6 secretion from nighttime (4 AM) to evening (7 PM) in insomniacs compared to controls (P <.05). Also, while TNF secretion in controls showed a distinct circadian rhythm with a peak close and prior to the offset of sleep (P <.05), such a rhythm was not present in insomniacs. Finally, daytime secretion of TNF in insomniacs was characterized by a regular rhythm of 4 hours (P <.05); such a distinct periodicity was not present in controls. We conclude that chronic insomnia is associated with a shift of IL-6 and TNF secretion from nighttime to daytime, which may explain the daytime fatigue and performance decrements associated with this disorder. The daytime shift of IL-6 and TNF secretion, combined with a 24-hour hypersecretion of cortisol, an arousal hormone, may explain the insomniacs' daytime fatigue and difficulty falling asleep.     

Nocturnal sleep and blood pressure in essential hypertension

Blood pressure and sleep-wakefulness patterns were monitored in the sleep laboratory over four consecutive nights in six patients with mild hypertension and six age- and sex-matched controls. In both hypertensives and normals, blood pressure levels decreased during sleep compared with presleep levels by 16.6 and 8.4%, respectively; levels for hypertensives, however, remained significantly above those for the normals. The nocturnal drop in blood pressure for both groups appeared to be related primarily to the general state of sleep rather than to any specific sleep stage. Nocturnal patterns of sleep stages and sleep cycling were almost identical for the two groups. Nocturnal blood pressure fluctuation was correlated positively with the distribution of nocturnal wakefulness in hypertensives but not in normotensives. This suggests that with hypertension there is some diminution of the dampening effect of sleep itself upon blood pressure which normally carries over into periods of nocturnal wakefulness. This alteration in patients with mild hypertension may reflect a decrease in the sensitivity of the baroreceptor reflex or some other pathophysiological process.     

Generalized cortical hyperostosis (Van Buchem disease): nosologic considerations.

Six of 41 presumed cases of Van Buchem disease described in the literature fit uniform diagnostic criteria. Segregation analysis of these 6 cases, in addition to another the authors report, supports a recessive mode of inheritance. Genetic heterogeneity is confirmed by the demonstration of a dominantly-inherited phenotype resembling Van Buchem disease. The probable etiology is a defect in the endochrondral modulatory step regulating transformation of osteoclast to osteoblast.     

Nocturnal sleep and wakefulness: effects of age and sex in normal sleepers

Sleep patterns were evaluated in 100 normal men and women who did not have any complaints of a sleep disorder and who were divided into three broad age groups: 19-29, 30-49, and 50-80 years. Total laboratory recording time was held constant across all four study nights. The amount of nightly wakefulness was positively correlated with age; total wake time for the oldest age group was about two times that of the youngest group, due primarily to an increase in wake time after sleep onset, because sleep latency did not change with age. Within each of the three age groups, especially the two oldest groups, the greatest amount of wakefulness following sleep onset occurred in the final hours of the recording period. Sleep in men was characterized by a higher number of nocturnal awakenings, and in elderly men by a longer final awakening; however, other parameters of sleep efficiency did not differ considerably between the sexes.     

Improved myocardial performance in postoperative cardiac surgical patients with sodium nitroprusside

Myocardial performance in the immediate postoperative period was studied 49 cardiac surgical patients treated with nitroprusside alone. With a thermodilution catheter positioned in the pulmonary artery, cardiac output was calculated and cardiac index, systemic vascular resistance index, and stroke work index were derived before after treatment with nitroprusside. The drug was a administered to all patients because of elevated systemic vascular resistance index. Based on their mean arterial pressure and cardiac index before treatment, the patients fell into two groups. Group I patients (N = 25) had elevated mean arterial pressure and normal cardiac index. Group II patients (N = 24) had normal mean arterial pressure and subnormal cardiac index. Nitroprusside administration resulted in a significant reduction of systemic vascular resistance index in all patients. In Group I the mean arterial pressure was lowered significantly while cardiac index increased only slightly. In Group II there was no change in arterial pressure, but cardiac index improved significantly. The results not only confirm that nitroprusside is effective in managing postoperative hypertension, but also demonstrate that in patients with postoperative left ventricular failure, the drug can improve cardiac output by reducing systemic vascular resistance without significantly lowering arterial blood pressure.     

Beneficial effects of alkalotic reperfusion following ischemic cardiac arrest.

The results of the present study indicate that exposure of ischemic myocardium to a solution with a low hydrogen ion concentration (pH 7.70) during the immediate post-ischemic period provides for better myocardial functional recovery and less myocardial water accumulation than does exposure to solutions with a normal hydrogen ion concentration (pH 7.40). Furthermore, exposure of the postischemic myocardium to a solution with a high hydrogen ion concentration (pH 7.10) results in poor recovery of ventricular function and significant myocardial water accumulation following reperfusion. Neither the beneficial effect of alkalotic reperfusion nor the harmful effect of acidotic reperfusion is associated with alterations in intramyocardial pCO₂ concentrations.