Time Periods in the Nasal Cycle During Night Sleep

The periodic congestion and decongestion of nasal venous sinuses and the alternation of airflow from one side of the nose to the other are referred to as a ‘nasal cycle’ in the literature. The aim of this study was to detect the nasal cycle during sleep in normal subjects and describe existing time periods and their sequence and patterns. We studied 58 records of the nasal cycle over 6–9 hours of sleep in six healthy volunteers and revealed that the cycle could be described as a combination of 1 to 4 discrete ultradian periods with various length: 1.0–1.5 h (mean 78.6min), 2.5–3.0 h (168.3 min), 4.0–4.5 h (260.3 min) or 5.5–6.0 h (347.5 min). The distribution of the discrete time periods was multi-modal and the mean lengths of periods were ‘multiples’ of a basic period of 85.4 min (?1.5 h) which was very close to the mean length of the sleep cycle (?1.5 h). In all subjects, during any of the REM stages of the sleep, an alternation of the airflow through the nostrils was observed. In about 75% of all cases, the switch of the flow between the nostrils occurred during the second or following REM stages of the sleep thus shaping a nasal cycle that contained mainly periods of 3.0 or 4.5 hours. We suggest a novel classification of the nocturnal nasal cyclicity and hypothesis that there is a relationship between the nasal cycle and the sleep cycle which, like other cyclic physiological phenomena with ultradian rhythmicity, expresses a pattern of ‘lateralisation’ that is synchronous with changes in the sleep cycle.     

Sleep/Wake Cycle Parameters and Sleep/Fatigue Complaints in Female Night Workers

Adaptation to shift-work is influenced by the way workers schedule their lives, including allocation of sleep episodes. Female workers (n = 29) engaged at an assembly line were studied as to individual differences in sleep parameters in order to verify whether those differences could be related to the manifestation of sleep and fatigue complaints. The sample was composed of women (20–40 y) working at night from Monday to Friday. Sleep data were based on daily sleep logs which were filled out by the workers for 10 consecutive weeks. In the analyses of sleep data both diurnal episodes between consecutive night shifts and noctural sleep episodes preceding working nights were taken into account. Worker's complaints were analyzed through questions extracted from an interview form encompassing questions on fatigue associated with the work schedule and on dissatisfaction with sleep on weekdays and weekends. The analysis of diurnal episodes showed no significant correlation between the total amount of sleep per day and the total number of complaints. Nevertheless, the latter was correlated to the length of the first sleep episode on a day, which usually began in the morning. As to sleep onset times, significant correlations were not detected concerning the first diurnal episodes. The analysis of nocturnal episodes did not reveal any significant correlation between sleep parameters and complaints. Results indicate that workers whose sleep onsets were allocated to the morning and were able to sleep for many consecutive hours, tended to show less complaints, suggesting that the temporal allocation of diurnal sleep and its length are relevant in the determination of how these workers perceive fatigue and sleep quality.     

Sleep/Wake Cycle Parameters and Sleep/Fatigue Complaints in Female Night Workers

Adaptation to shift-work is influenced by the way workers schedule their lives, including allocation of sleep episodes. Female workers ( n = 29) engaged at an assembly line were studied as to individual differences in sleep parameters in order to verify whether those differences could be related to the manifestation of sleep and fatigue complaints. The sample was composed of women (20-40 y) working at night from Monday to Friday. Sleep data were based on daily sleep logs which were filled out by the workers for 10 consecutive weeks. In the analyses of sleep data both diurnal episodes between consecutive night shifts and noctural sleep episodes preceding working nights were taken into account. Worker's complaints were analyzed through questions extracted from an interview form encompassing questions on fatigue associated with the work schedule and on dissatisfaction with sleep on weekdays and weekends. The analysis of diurnal episodes showed no significant correlation between the total amount of sleep per day and the total number of complaints. Nevertheless, the latter was correlated to the length of the first sleep episode on a day, which usually began in the morning. As to sleep onset times, significant correlations were not detected concerning the first diurnal episodes. The analysis of nocturnal episodes did not reveal any significant correlation between sleep parameters and complaints. Results indicate that workers whose sleep onsets were allocated to the morning and were able to sleep for many consecutive hours, tended to show less complaints, suggesting that the temporal allocation of diurnal sleep and its length are relevant in the determination of how these workers perceive fatigue and sleep quality.     

Changes in Sleep Time and Sleep Quality across the Ovulatory Cycle as a Function of Fertility and Partner Attractiveness

Research suggests that near ovulation women tend to consume fewer calories and engage in more physical activity; they are judged to be more attractive, express greater preferences for masculine and symmetrical men, and experience increases in sexual desire for men other than their primary partners. Some of these cycle phase shifts are moderated by partner attractiveness and interpreted as strategic responses to women''s current reproductive context. The present study investigated changes in sleep across the ovulatory cycle, based on the hypothesis that changes in sleep may reflect ancestral strategic shifts of time and energy toward reproductive activities. Participants completed a 32-day daily diary in which they recorded their sleep time and quality for each day, yielding over 1,000 observations of sleep time and quality. Results indicated that, when the probability of conception was high, women partnered with less attractive men slept more, while women with more attractive partners slept less.     

Plasmodium falciparum: Increased and Multiple Invasion During Short Periods of Time

We describe how to obtain an increased merozoite invasion of Plasmodium falciparum into human erythrocytes during short periods of time. Using this procedure, infected erythrocytes show multiple invasions (2–4 merozoites per erythrocyte), amplifying, several times, the effects of parasite entry into host cells. The procedure yields synchronous cultures (2-h age range) with parasitemia as high as 15%. It is possible to reach parasitemia of 50% or higher allowing for a 6-h invasion period.     

Respiration During Sleep in Children

In 22 children (11 boys and 11 girls), aged 9 to 13 years, respiration was monitored during one night of sleep. No child had a significant history of breathing problems during sleep. Sleep was recorded using standard techniques (electroencephalography, electrooculography, electromyography), and respiration was measured with nasal thermistors and abdominal or thoracic strain gauges. Respiratory pauses (five seconds or longer) were determined for all sleep stages. Respiratory rate was scored only in the first and last sleep cycles and during ten waking minutes before sleep onset. Respiratory rate was significantly affected by wakefulness or stage of sleep: highest in wakefulness and stage 1, lowest in stage 2 of the last sleep cycle. Regularity of respiratory rate showed a similar effect. Variance of respiratory rate was significantly lower in girls than boys. Respiratory pauses during sleep were seen in every child, ranging from 3 to 40 pauses per night (average, 17.2 for boys and 18.0 for girls). Significantly greater numbers of pauses per minute were seen in stage 1 and rapid eye movement (REM) sleep than in stages 2, 3 and 4. The longest respiratory pause was 25 seconds. The conclusion is made that a small number of respiratory pauses during sleep are normal in children of this age.     

笼养海南(开鸟)的活动时间分配

2003年10月至2004年4月,在对海南[开鸟]进行驯养的基础上,采用全部事件取样法研究了笼养海南[开鸟]的活动时间分配。结果表明：笼养海南[开鸟]一天中除静栖和静立外,其余各行为所占时间比例在白天极少,而在晨（5：00～7：00am）、昏（19：00～21：00pm）和午夜（23：00～1：00am）较大,呈明显的日活动节律;节律变化与季节有关;海南[开鸟]各种行为活动所占比例依次为静栖82．48％、静立8．64％、运动5．36％、取食1．97％、身体护理1．30％、其它0．25％。其时间分配不受季节（春、秋、冬季）影响。     

Tryptophan Metabolism During the Menstrual Cycle

The metabolism of tryptophan and tryptophan metabolites was investigated during the follicular, luteal and premenstrual phases of the menstrual cycle in 33 healthy women across one cycle. The metabolites of all three pathways of tryptophan ie the serotonergic pathway, the pyrollase pathway and the indole acetic acid pathway, were assayed from urinary prebreakfast samples collected on a repeated measures basis. Urinary 3 hydroxy kynurenine excretion was significantly elevated in the luteal phase (p=0.030). The relative activity of the serotonergic pathway to the kynurenergic pathway (identified by the ratios 5HT+HIAA/KY+HK and 5HT/KY+HK) were significantly elevated in both the luteal and premenstrual phases compared to the follicular phase (p=0.009 and p=0.005 respectively); indicating that the kynurenergic pathway of tryptophan metabolism may modulate serotonergic metabolism (via HK) during the menstrual cycle; and that the relative and not actual levels of serotonin metabolism may be the important factor when investigating any cyclical effects of the neurotransmitter serotonin.     

The Time of DNA Synthesis During the Interdivision Growth Cycle of Tetrahymena pyriformis Fed on Living Bacteria

SYNOPSIS. It has been possible to obtain selective labeling of the macronucleus of Tetrahymena pyriformis fed on living Escherichia coli. The bacteria themselves, a thymidine requiring mutant, were labeled by exposure to tritiated thymidine in a lettuce infusion medium supplemented with trypticase broth. Various patterns of labeling were seen in synchronized Tetrahymena when the radioactive bacteria were given at particular times during the growth cycle. These patterns have been interpreted as indicating the duration of the G₁, S, and G₂ periods; they also suggest that a soluble pool of thymine exists in this animal from one S period to the next.     

Cardiac Autonomic Activity During Human Sleep: Analysis of Sleep Stages and Sleep Cycles

In this study characteristics of cardiac functioning were investigated in nine subjects during their nocturnal sleep. The pre-ejection period and the high frequency component of heart rate variability were used as indices of cardiac sympathetic and parasympathetic activity of the autonomic nervous system respectively. Heart rate and the autonomic indices were assessed across physiological determined sleep stages and consecutive temporal sleep cycles. Repeated measures ANOVA analyses indicated a significant pattern of heart rate as a function of sleep stages, which was mirrored by parasympathetic activity. Further, a significant decrease of heart rate as a function of sleep cycles was mirrored by an increase of sympathetic activity. Moreover, non-REM/REM differences revealed a dominant role of parasympathetic activity during sleep stages as well as sleep cycles. These findings demonstrate that sympathetic activity is influenced by time asleep, whereas parasympathetic activity is influenced by the depth of sleep.     

Cardiac Autonomic Activity During Human Sleep: Analysis of Sleep Stages and Sleep Cycles

In this study characteristics of cardiac functioning were investigated in nine subjects during their nocturnal sleep. The pre-ejection period and the high frequency component of heart rate variability were used as indices of cardiac sympathetic and parasympathetic activity of the autonomic nervous system respectively. Heart rate and the autonomic indices were assessed across physiological determined sleep stages and consecutive temporal sleep cycles. Repeated measures ANOVA analyses indicated a significant pattern of heart rate as a function of sleep stages, which was mirrored by parasympathetic activity. Further, a significant decrease of heart rate as a function of sleep cycles was mirrored by an increase of sympathetic activity. Moreover, non-REM/REM differences revealed a dominant role of parasympathetic activity during sleep stages as well as sleep cycles. These findings demonstrate that sympathetic activity is influenced by time asleep, whereas parasympathetic activity is influenced by the depth of sleep.     

Sleep Cystometrography: A Preliminary Study of Bladder Function During Sleep

Bladder function during sleep was studied by the use of a cystometer which recorded detrusor contractions and intravesical pressure as urine accumulated in the bladder during diuresis. The cystometrographic tracing was obtained while the patient was awake. A detrusor contraction can occur during sleep. Results of such studies on five patients are presented, with photographs of representative cystometrographic tracings.The general pattern of the cystometrogram during sleep was found to be different from that obtained while the patient was awake. A detrusor contraction can occur during sleep and may subsequently: (a) subside without awakening the patient; (b) be associated with the involuntary escape of urine or flatus; or (c) cause the patient to awaken. It is suggested that detrusor contractions rather than increases in urinary volume are responsible for the individual''s awakening at night to urinate.In the light of these observations, further study of patients with enuresis and those with non-obstructive nocturia is required.     

The Night Is Young: Sexuality in Mexico in the Time of AIDS

The Night Is Young: Sexuality in Mexico in the Time of AIDS. Héctor Carrillo. Chicago: University of Chicago Press, 2002. 352 pp.     

Growth in Volume of Euglena gracilis During the Division Cycle

The distribution of volumes of Euglena gracilis cells was measured conductimetrically. The volume spectrum of cultures in balanced growth was analyzed by the method of Collins and Richmond. The kinetics of volume increase of Euglena is neither linear nor exponential; the growth rate of small and large cells is low, but intermediate size cells show the largest growth rate.