Search results for "circadian"
showing 10 items of 363 documents
Insomnia symptoms combined with nocturnal hypoxia associate with cardiovascular comorbidity in the European sleep apnea cohort (ESADA)
2018
WOS: 000482433800011
Assessment of various factors influencing esophageal pressure measurement. II. Significance of physiological factors in intraluminal manometry.
1980
In the second part of this study the effect of age, sex, body size, body weight and timing of the manometric examination (morning vs. noon) on esophageal pressure measurement was investigated in a total of 119 healthy subjects, using an electromagnetic microtransducer. Additionally intraindividual variation of pressures was studied over a period of 6 months. Of these parameters only age influenced upper esophageal sphincter (UES) pressure significantly: The mean UES pressure of younger subjects (20-49 years) was significantly higher (144.4 +/- 8.6 mmHg) compared to that of older subjects (50-80 years) where a mean pressure of 103.4 +/- 7.2 mmHg was recorded (p less than 0.0005). Intraindivi…
Frontoparietal cortex and cerebellum contribution to the update of actual and mental motor performance during the day
2016
AbstractActual and imagined movement speed increases from early morning until mid-afternoon. Here, we investigated the neural correlates of these daily changes. Fifteen subjects performed actual and imagined right finger opposition movement sequences at 8 am and 2 pm. Both actual and imagined movements were significantly faster at 2 pm than 8 am. In the morning, actual movements significantly activated the left primary somatosensory and motor areas, and bilaterally the cerebellum; in the afternoon activations were similar but reduced. Contrast analysis revealed greater activity in the cerebellum, the left primary sensorimotor cortex and parietal lobe in the morning than in the afternoon. Im…
Diurnal Variation in Maximal and Submaximal Strength, Power and Neural Activation of Leg Extensors in Men: Multiple Sampling Across Two Consecutive D…
2007
This study aimed to compare day-to-day repeatability of diurnal variation in strength and power. Thirty-two men were measured at four time points (07 : 00 - 08 : 00, 12 : 00 - 13 : 00, 17 : 00 - 18 : 00, and 20 : 30 - 21 : 30 h) throughout two consecutive days (day 1 and day 2). Power during loaded squat jumps, torque and EMG during maximal (MVC) and submaximal (MVC40) voluntary isometric knee extension contractions were measured. The EMG/torque ratio during MVC and MVC40 was calculated to evaluate neuromuscular efficiency. A significant time-of-day effect with repeatable diurnal patterns was found in power. In MVC, a significant time-of-day effect was present on day 2, whereas day 1 showed…
Diurnal Rhythm of the Muscular Performance of Elbow Flexors During Isometric Contractions
1996
The influence of time of day on elbow flexion torque was studied. Thirteen physical education students, 7 males and 6 females, made maximal and submaximal isometric contractions at 90 degrees of elbow flexors using a dynamometer. The torque developed was measured on each contraction. The myoelectric activity of the biceps muscle was also measured at the same time by surface electromyography (EMG) and quantified from the root mean square (RMS) activity. Torque and surface EMGs were measured at 6:00, 9:00, 12:00, 15:00, 18:00, 21:00, and 24:00 h over the same day. Oral temperature before each test session was measured on each occasion after a 30-min rest period. We observed a diurnal rhythm i…
Circadian rhythms in human muscular efficiency: continuous physical exercise versus continuous rest. A crossover study.
2000
This study deals with the influence of time of day on neuromuscular efficiency in competitive cyclists during continuous exercise versus continuous rest. Knee extension torque was measured in ultradistance cyclists over a 24h period (13:00 to 13:00 the next day) in the laboratory. The subjects were requested to maintain a constant speed (set at 70% of their maximal aerobic speed obtained during a preliminary test) on their own bicycles, which were equipped with cyclosimulators. Every 4h, torque developed and myoelectric activity were estimated during maximal isometric voluntary contractions of knee extensors using an isokinetic dynamometer. Mesenteric temperature was monitored by telemetry.…
Effects of REM sleep awakenings and related wakening paradigms on the ultradian sleep cycle and the symptoms in depression.
2002
In 1975 Vogel and coworkers published their classical study where they compared selective rapid eye movement (REM) sleep deprivation by brief awakenings to a control intervention paradigm in depressed patients. The superior antidepressive impact of the first procedure was attributed to the REM pressure accumulating during the treatment period. The laborious procedure and the considerable effort necessary to evaluate the sleep profiles in real time have prevented similar experiments so far. Based on artificial neural networks we developed a software for the real time detection of REM sleep. In combination with an alarm system the algorithm allowed us to wake up subjects automatically and to …
Estimation of pharmacokinetic parameters of lithium from saliva and urine
1974
The salivary and urinary excretion of lithium was studied in three healthy male sub;ects after oral administration of two or three different doses. In all individuals the concentration of lithium in salivary fluid was found to be 2.2 to 3.3 times as high as the concentration in plasma. In each sub;ect the saliva:plasma concentration ratio remained constant over more than a 100 fold concentration range for at least 3 months. This ratio was not markedly affected by about tenfold changes in saliva flow rate. Thus, pharmacokinetic parameters obtained from salivary excretion data are in agreement with those obtained from plasma concentration and urinary excretion rate data, and renal clearance o…
Sleep-electroencephalography and the secretion of cortisol and growth hormone in normal controls.
1987
Abstract. Sleep-electroencephalography, and the nocturnal secretion of cortisol and GH were investigated simultaneously in a sample of 25 male normal controls (27.1 ± 1.3 years) in order further to examine interaction between sleep structure and concurrent endocrine activity. Slow wave sleep activity was increased during the first part of the night, whereas cortisol concentration was low and GH output reached maximal levels. The second half of the night was characterized by a relative preponderance of REM-sleep, low GH-concentration, and an increase in cortisol. However, no distinct reciprocal interaction between cortisol and GH concentration was noted. In all subjects, a pronounced GH surg…
Sleepiness, sleep, and use of sleepiness countermeasures in shift-working long-haul truck drivers
2015
Driver sleepiness is a prevalent phenomenon among professional drivers working unconventional and irregular hours. For compromising occupational and traffic safety, sleepiness has become one of the major conundrums of road transportation. To further elucidate the phenomenon, an on-road study canvassing the under-explored relationship between working hours and sleepiness, sleep, and use of sleepiness countermeasures during and outside statutory rest breaks was conducted. Testing the association between the outcomes and working hours, generalized estimating equations models were fitted on a data collected from 54 long-haul truck drivers (mean 38.1 ± 10.5 years, one female) volunteering in the…