Changes in the stages of nocturnal sleep in man with a lesion of the hypothalamus-brain stem structures]

Polygraphic study of nocturnal sleep in 18 patients with affection of the hypothalamo-mesencephalic structures showed a reduction of the duration of the II stage and a prolongation of the III and IV stages of slow sleep in comparison with the corresponding indices in the patients with involvement of the ponto-bulbar structures (9) and in healthy persons (8) of control group. Analysis of the qualitative indices of the EEG of slow sleep (a relative amount of the sleep spindles per 1 min of the II stage, delta-index and the delta-wave amplitude at the II and the IV stages) demonstrated a tendency to their increase in the patients with affection of the hypothalamo-mesencephalic structures. Patients of this group showed a decreased frequency of spontaneous changes of sleep from deeper to more superficial stages.     

Recurrence analysis of nocturnal heart rate in sleep apnea patients.

This study examines the utility of recurrence analysis in the field of sleep apnea detection from heart rate series. In 38 patients, ECGs were recorded during sleep in parallel to polysomnography (PSG). Parameters extracted from distance matrices and from recurrence plots (RPs) of the time-delay embedded RR series were tested for their suitability to detect minute-by-minute phases of sleep apnea by means of receiver operating curve (ROC) analysis against the findings of the PSG. Features derived from the continuous distance matrix yielded better results (sensitivity 77%; specificity 78%) than those quantifying the structure of the binary RP (67% and 74%, respectively), accentuating the significance of information on the magnitude of heart rate variations for sleep apnea detection. However, simpler and computationally less demanding spectral techniques yield largely comparable results (77% and 72%, respectively). This raises the question as to whether recurrence analysis of RR series yields additional insight into sleep apnea recognition from heart rate variations.     

Development of the nocturnal sleep electroencephalogram in human infants

The development of nocturnal sleep and the sleep electroencephalogram (EEG) was investigated in a longitudinal study during infancy. All-night polysomnographic recordings were obtained at home at 2 wk and at 2, 4, 6, and 9 mo after birth (analysis of 7 infants). Total sleep time and the percentage of quiet sleep or non-rapid eye movement sleep (QS/NREMS) increased with age, whereas the percentage of active sleep or rapid eye movement sleep (AS/REMS) decreased. Spectral power of the sleep EEG was higher in QS/NREMS than in AS/REMS over a large part of the 0.75- to 25-Hz frequency range. In both QS/NREMS and AS/REMS, EEG power increased with age in the frequency range <10 Hz and >17 Hz. The largest rise occurred between 2 and 6 mo. A salient feature of the QS/NREMS spectrum was the emergence of a peak in the sigma band (12-14 Hz) at 2 mo that corresponded to the appearance of sleep spindles. Between 2 and 9 mo, low-frequency delta activity (0.75-1.75 Hz) showed an alternating pattern with a high level occurring in every other QS/NREMS episode. At 6 mo, sigma activity showed a similar pattern. In contrast, theta activity (6.5-9 Hz) exhibited a monotonic decline over consecutive QS/NREMS episodes, a trend that at 9 mo could be closely approximated by an exponential function. The results suggest that 1) EEG markers of sleep homeostasis appear in the first postnatal months, and 2) sleep homeostasis goes through a period of maturation. Theta activity and not delta activity seems to reflect the dissipation of sleep propensity during infancy.     

Plasma testosterone during nocturnal sleep in normal men

Plasma testosterone was measured by a competitive protein binding procedure at 10 to 20 minute intervals in five normal adult men during two nights of sleep. Blood samples were obtained by means of an indwelling venous catheter while sleep was monitored polygraphically. There were 1–4 abrupt elevations of plasma testosterone concentration per night in each of the subjects with an average increase of 244 ng/100 ml ± 45.5 (SE) or 59% above the values present at the onset of the episode. The fluctuations in plasma testosterone were superimposed on a nocturnal rise of the hormone observed in seven of the nights. The average of all samples taken during each hour period through the ten nights revealed a highly significant (P<0.001) nocturnal increase in plasma testosterone. The findings did not support the existence of a relation between REM sleep and an increase in testosterone levels.     

Effect of sleep on nocturnal bronchoconstriction and ventilatory patterns in asthmatics

To assess the effect of sleep on airflow resistance and patterns of ventilation in asthmatic patients with nocturnal worsening, 10 adult subjects (6 asthmatic patients with nocturnal worsening, 4 normal controls) were monitored overnight in the sleep laboratory on two separate occasions. During 1 night, subjects were allowed to sleep normally, whereas during the other night all sleep was prevented. The six asthmatic patients demonstrated progressive increases in lower airway resistance (Rla) on both nights, but the rate of increase was twofold greater (P less than 0.0001) during the sleep night compared with the sleep prevention night. However, overnight decrements in forced expired volume in 1 s (FEV1) were similar over the 2 nights. The asthmatic patients maintained their minute ventilation as Rla increased during sleep, demonstrating a stable tidal volume with a mild increase in respiratory frequency. We conclude that in asthmatic patients with nocturnal worsening 1) Rla increases and FEV1 falls overnight regardless of sleep state, 2) sleep enhances the observed overnight increases in Rla, and 3) sleep does not abolish compensatory ventilatory responses to spontaneously occurring bronchoconstriction.     

Factor VIII: structure, function and analysis

Factor VIII is an important blood coagulation protein whose genetic deficiency leads to the serious bleeding disorder, classic haemophilia (haemophilia A).Here we review the structure, function and analysis of this protein for diagnostic and therapeutic applications. Because factor VIII is tightly associated with von Willebrand factor some recent work on the latter is also considered so as to clarify the relationship between them.     

Alpha-delta sleep in a patient with nocturnal panic attacks

Sleep and Biological Rhythms - We report here on our finding of an alpha-delta sleep in a 40-year-old-female patient suffering from panic attacks, including nocturnal panic attacks, who complained...     

Slow-wave sleep in daytime and nocturnal sleep: an estimate of the time course of "Process S"

Daan et al. (1984) have proposed that sleep and wakefulness are regulated, in part, by a "Process S" that increases during wakefulness and declines during sleep. Data derived from several studies were taken to determine the time course of Process S during both wakefulness and sleep. As required by the model, slow-wave-sleep (SWS; an index of Process S) was found to increase exponentially as a function of prior wake time (equation 1) and to decline exponentially as a function of time asleep (equation 2). The equations accounted for 91% and 96% of the variance, respectively. In addition, equation 1 accurately predicted the amount the amount of SWS in the first hour of nocturnal sleep.     

Daytime noise and subsequent night sleep in man

The effects of daytime noise on recovery processes during subsequent undisturbed night sleep were studied in six healthy men (21-27 years), exposed to 80 dB (A) pink noise 8 h per day for 2 days. Sleep EEG, ECG, and respiration were recorded in the laboratory for five consecutive nights: two baseline nights, two nights following noise stimulation, and again one baseline night. Additionally questionnaire data were collected, reflecting a subjective impairment of the recovery function of sleep after noise exposure. EEG sleep data of the first post-noise night showed an increase in slow wave sleep with a simultaneous decrease in stage 2 sleep. During the second post-noise night these changes were less prominent. Three subjects additionally showed an instability in the sleep course coinciding with elevated heart and respiration rates. However, altogether the autonomic parameters were not clearly affected by the noise exposure. The findings support the assumption that strong daytime noise may interfere with subsequent sleep processes.