Unlike other organs that operate continuously, such as the heart and kidneys, many of the operations of the nervous system shut down during sleep. The evolutionarily conserved unconscious state of sleep that puts animals at risk from predators indicates that it is an indispensable integral part of systems operation. A reasonable expectation is that any hypothesis for the mechanism of the nervous system functions should be able to provide an explanation for sleep. In this regard, the semblance hypothesis is examined. Postsynaptic membranes are continuously being depolarized by the quantally-released neurotransmitter molecules arriving from their presynaptic terminals. In this context, an incidental lateral activation of the postsynaptic membrane is expected to induce a semblance (cellular hallucination of arrival of activity from its presynaptic terminal, which forms a unit for internal sensation) of the arrival of activity from its presynaptic terminal as a systems property. This restricts induction of semblance to a context of a very high ratio of the duration of the default state of neurotransmitter-induced postsynaptic depolarization to the total duration of incidental lateral activations of the postsynaptic membrane. This requirement spans within a time-bin of a few sleep-wake cycles. Since the duration of quantal release remains maximized, the above requirement can be achieved only by ceiling the total duration of incidental lateral activations of the postsynaptic membrane, which necessitates a state of sleep.
Keywords: Quantal release, Duration of quantal release, Systems requirement for sleep, Semblance, Semblance hypothesis, Lateral postsynaptic activation
The first case of video-polysomnography (vPSG) documented sleep masturbation in a male is reported, and the second reported case of shift work induced sexsomnia. A 20 y.o. soldier with childhood sleep-walking (SW) developed sleep masturbation and SW triggered by military shift work. vPSG documented two episodes of sleep masturbation from N2 sleep in the fourth sleep cycle and from N3 sleep during the fifth sleep cycle. There was no sleep-disordered breathing nor periodic limb movements. vPSG thus confirmed confusional arousals from NREM sleep as the cause of the masturbation. Bedtime clonazepam therapy controlled the SW but not the masturbation.
Keywords: sexsomnia, Sexual behaviors in sleep, Masturbation, Parasomnia, Video-polysomnography, Shift work, NREM sleep, Sleepwalking, Clonazepam
BACKGROUND: We investigate the potential usability of a novel in-the-ear electroencephalography recording device for sleep staging.
METHODS: In one healthy subject we compare simultaneous earelectroencephalography to standard scalp EEG visually and using power spectrograms. Hypnograms independently derived from the records are compared.
RESULTS: We find that alpha activity, K complexes, sleep spindles and slow wave sleep can be visually distinguished using earelectroencephalography. Spectra! peaks are shared between the two records. Hypnograms are 90.9% similar.
CONCLUSION: The results indicate that ear-electroencephalography can be used for sleep staging.
Keywords: Ear-EEG, Sleep staging, Long term monitoring, Polysomnography, Electroencephalography, Personal device
This work aimed to determine daytime sleepiness and sleep complaints prevalence and the corresponding influence on perceived fatigue and to evaluate the influence of sociodemographic parameters and labour variables on sleep complaints, sleepiness and fatigue.
A questionnaire was developed including socio-economic and labour issues and instruments, focused in sleep and fatigue. The response rate was 32% and the final sample had 435 pilots.
The prevalence of sleep complaints was 34.9%, daytime sleepiness 59.3% and fatigue 90.6%.
The high prevalence of sleep complaints, sleepiness and fatigue was disclosed in pilots, with those who fly short/medium having an added risk of fatigue.
Keywords: Prevalence, Sleep, Predictors, Shiftwork, Jetlag
PURPOSE: Despite progress in research concerning adolescent and young adult sleep and circadian preferences, several aspects have remained unexamined. This study explored gender and diurnal rhythms in relation to several sleep-related factors: sleep duration, bedtime, wake-up time, tiredness, sleepiness, and optimal subjective sleep duration
METHODS: Circadian preferences and sleep were investigated in 555 (Females N=247) Finnish students aged 15-20. The self-report measures included a shortened version of the Horne-Ostberg Morningness-Eveningness Scale, the Epworth Sleepiness Scale as well as items probing feelings of tiredness, optimal subjective sleep durations, and bedtime and wake-up time on the most recent day and a typical weekend. Data were collected from Tuesday to Thursday during an ordinary school week.
RESULTS AND CONCLUSION: The most frequent chronotype was the intermediate type (54%), and compared to previous studies, the prevalence of evening-oriented individuals was high (37%), whereas only 9% of the participants were classified as morning oriented. No gender-specific or chronotype-specific differences in sleep durations were observed, but girls/women and evening-orientated individuals reported suffering more from sleepiness, compared to boys/men and more morning-typed participants, respectively. About 20% of the total sample indicated that their subjective need for sleep was not satisfied during the weekdays nor the weekend, indicating chronic sleep deprivation. Among girls/women and evening-oriented individuals, the subjective sleep need was greater for weekday nights.
Keywords: Diurnal, Sleepiness, Chronotype, Sleep deprivation, Gender, Optimal sleep length
INTRODUCTION: Sleep movement disorders includes mainly periodic limb movement and others. The more frequent breathing disorders are: obstructive sleep apnea-hypopnea syndrome and primary snoring. Objective: To compare sleep architecture in periodic limb movements and breathing disorders of different severity, and weight their interactions.
METHODS: We compared sleep architecture in 160 patients, divided in six groups: periodic limb movements (n=25), obstructive apnea only (n=30), periodic limb movements/snoring (n=30), periodic limb movements/mild apnea (n=25), periodic limb movements/moderate apnea (n=25), periodic limb movements/severe apnea (n=26). Polysomnographic variables were compared by analysis of variance and Tukey test.
RESULTS: We observed an increase of percentage of awakenings in the group with periodic limb movements/severe apnea. We found an increase of percentage of light sleep in the group with obstructive apnea only with respect to periodic limb movements group. The group with obstructive apnea only presented less rapid eye movements sleep in relation with group with periodic limb movements. We found an increase of awakenings in the group with periodic limb movements/severe apnea to the group with periodic limb movements only. Oxygen saturation showed a decrease in the group with periodic limb movements/severe apnea and obstructive apnea only group to periodic limb movements only group.
CONCLUSIONS: Periodic limb movements and breathing disorders, resulted in more additive changes in sleep architecture alterations, than as separately disorders, in a complex interaction. Research in these relations deserve more investigations.
Keywords: Periodic limb movements disorder, Obstructive sleep apnea-hypopnea syndrome, Sleep architecture, Polysomnography
In the postero-lateral hypothalamus are located two neuronal systems that utilize the neuropeptides melanin-concentrating hormone (MCH) and hypocretins (also called orexins) as neuromodulators. These systems have reciprocal connections between them, and project throughout the central nervous system. MCH has been involved in the generation of sleep, mainly REM sleep, while hypocretins have a critical role in the generation of wakefulness.
MCHergic activity is also involved in the pathophysiology of major depressive disorder (MD). In this regards, intracerebral administration of MCH promotes pro-depressive behaviors (i.e., immobility in the forced swimming test) and REM sleep hypersomnia, which is an important trait of depression. Furthermore, the antagonism of the MCHR-1 receptor has a reliable antidepressant effect, suggesting that MCH is a pro-depressive factor. Hypocretins have been also involved in mood regulation; however, their role in depression is still on debate.
Taking these data into account, we explored whether systemic subchronical treatment with Fluoxetine (FLX), a serotonergic antidepressant, modifies the concentration of MCH in the cerebrospinal fluid (CSF), as well as the preproMCH mRNA expression. We also evaluated the hypocretinergic system by quantifying the hypocretin-levels in the CSF and the preprohypocretin mRNA expression.
Compared to control, FLX increased the levels of preprohypocretin mRNA without affecting the hy-pocretin-1 CSF levels. On the contrary, FLX significantly decreased the MCH CSF concentration without affecting the preproMCH gene expression. This result is in agreement with the fact that MCH serum level diminishes during the antidepressant treatment in MD, and supports the hypothesis that an increase in the MCHergic activity could have pro-depressive consequences.
Keywords: Neuropeptides, Hypocretin, Orexin, Depression, Antidepressant, Melanin-concentrating hormone
INTRODUCTION: Up to 84% of prematurely born infants suffer hypoxic, anoxic, and ischemic insults. Those infants with subsequent behavioral, motor or cognitive dysfunction represent 8-11% of all live births. Yet, no interventions employed during pregnancy attenuate risk of morbidity in those at-risk infants. Dietary supplementation with omega-3 polyunsaturated fatty acids (ω-3 PUFAs) has been shown to reduce stroke-induced neuropathology in rat models emulating this adverse clinical event. To extend those studies we sought to determine whether maternal dietary supplementation with ω-3 PUFAs would confer neuroprotection against hypoxia-induced neurochemical dysfunction in newborn rat pups exposed to repetitive hypoxic insults.
METHODS: We provided pregnant rats with either a ω-3 PUFA enriched diet or else a standard rat chow diet. At postnatal day 7, pups were assigned randomly to either repetitive hypoxic insults or repetitive bursts of room air. On postnatal day 12, pups were sacrificed and brain dopamine levels characterized.
RESULTS: Baseline brain dopamine levels did not differ between rat pups born to dams who received ω-3 PUFA enriched versus standard rat chow diets. Rat pups born to dams maintained on normal diets, who were exposed to five days of repetitive hypoxic insults, experienced a 57% reduction in striatal dopamine levels accompanied by significant apoptosis. In contrast, ω-3 PUFA-enriched newborn pups experienced no loss in striatal dopamine levels, and only minimal apoptosis.
CONCLUSIONS: Our findings suggest that it may be feasible to confer neuroprotection against hypoxia-induced dopamine dysfunction to newborns likely to experience hypoxic insults. This could significantly improve the outcomes of those 8-11% of newborns who would otherwise experience hypoxia-induced behavioral, motor and cognitive dysfunction.
Keywords: Hypoxia, Dopamine, Neuroprotection, Fatty acids, Perinatal
STUDY OBJECTIVES: To determine the prevalence of sleep complaints in adults in Colombia at different altitudes.
DESIGN: Cross-sectional, population-based and observational study.
SETTING: Urban areas in three cities (Bogotá, Bucaramanga, Santa Marta) located between 15 and 2640 masl. Subjects Over 18 years old.
INTERVENTIONS: Epworth sleepiness scale (ESS), Pittsburgh sleep quality index (PSQI), Berlin questionnaire, STOP-Bang questionnaire and diagnostic criteria for restless leg syndrome (IRLSSG).
MEASUREMENTS AND RESULTS: The overall prevalence of sleep complaints was 59.6% (CI 95%: 57.3; 61.8%). According to the Pittsburgh scale, 45.3% (CI 95%: 43.0; 47.5) required medical assistance. The Berlin questionnaire indicated that 19.0% (CI 95%: 17.3; 20.8%) had a high risk of sleep apnea (OSA) compared to 26.9% (CI 95%: 24.9; 29.0%) according to STOP-Bang. Among the subjects, 13.7% (CI 95%: 12.3; 15.3%) had excessive daytime sleepiness and 37.7% (CI 95%: 35.5; 39.8%) had a restless leg syndrome. When comparing cities, significant differences in the overall frequency of subjects requiring care were found between Santa Marta (higher frequency) and the other two cities. Differences in sleep problem frequency (Pittsburgh) were observed between Bogota (higher frequency) and Bucaramanga and also between Santa Marta (higher frequency) and the other two cities. The high risk of OSA (STOP-Bang) was different between Bogota (higher frequency) and Bucaramanga and also between Santa Marta (high frequency) and Bucaramanga.
CONCLUSIONS: We observed a high prevalence of sleep complaints with significant differences among the cities, indicating a need to pay a greater attention to these problems.
Keywords: Sleep complaints, Diagnostic tests, Altitude
OBJECTIVES: To evaluate the risk of obstructive sleep apnea (OSA) in a primary care population of elderly Nigerians and to determine its correlates.
METHODS: Clinical and demographic data of 414 elderly individuals in a primary care clinic were obtained. Their risk of OSA was estimated using Berlin questionnaire while Epworth sleepiness scale and the Center for Epidemiologic Studies Depression Scale (CESD-10) were also administered.
RESULTS: Of the 414 subjects, 96 (23.2%) met the criteria for a high risk for OSA with a male to female ratio of 1:1. Subjects at high OSA risk (high OSA risk group) were younger than those at low OSA risk (low OSA risk group) (71.4±6.8 vs 73.6±7.7, p=0.011). Mean body mass index (BMI, kg/m2) (27.3±5.8 vs 24.7±5.1, p < 0.001) and waist circumference (WC, cm) (90.7±13.1 vs 86.5±13.9, p= 0.011) were higher in the high OSA risk group compared with the low OSA risk group. A total of 215 (51.9%) and 62 (15.0%) subjects had clinically significant depressive symptoms (CESD-10 score ≥ 10) and excessive daytime sleepiness (EDS), respectively. On regression, the odds of EDS, depressive symptoms, increased BMI and younger age were significantly higher in the high OSA risk group compared with the low OSA risk group.
CONCLUSIONS: High risk for OSA and depressive symptoms are common in our sample of elderly Nigerians. Depressive symptoms, EDS, BMI and age independently predict high OSA risk in the elderly.
Keywords: Obstructive sleep apnea, Elderly, Nigeria, Prevalence, Primary care, Predictors
The present study examined whether a nap after complex motor learning enhanced the following day's physical performance. Eighteen volunteers met the inclusion criteria and were assigned to either a nap (n=9; men= 5; mean age=21.0±1.5) or no-nap group (n=9; men= 5; mean age=21.9±0.3). Participants practiced juggling in the morning and were tested immediately afterwards. Participants of the nap group were given a 70-minute nap opportunity after juggling practice, while the no-nap group stayed awake. Juggling performance was then tested in the evening (retest-1) and the next morning (retest-2). Two-way analysis of variance (group: nap, no-nap x time: test, retest-1, retest-2) found there was a significant effect of test time and a significant group x time interaction. The juggling performance of both groups improved from test to retest-1, respectively. However, the juggling performance level of the nap group was higher than that of the no-nap group at the retest-1. As predicted, a nap promptly after learning motor skills was associated with subsequently improved performance. Moreover, the juggling performance of the nap group showed additional significant improvements in the retest-2. In the no-nap group, however, there were no significant improvements in the juggling performance after nocturnal sleep. These results demonstrate that the benefits of a nap following learning were further enhanced after nocturnal sleep. The present results may provide justification for introducing nap periods into daily athletic training as an active method to improve performance.
Keywords: Motor learning, Motor skills, Memory consolidation, Nap, Sleep
The aim of this study was to evaluate the association between sleeping habits, Mediterranean diet pattern, and weight status in an adolescent population. The sample consisted of 1586 individuals aged 11 -14 years attending 15 secondary schools of Sicily, Southern Italy. School were randomly selected and the data collected during two school years. Anthropometric data was collected and body composition was assessed by bioelectrical impedance analysis. Demographic information, sleep duration, pediatric daytime sleepiness questionnaire (PDSS), physical activity and dietary habits (including adherence to the Mediterranean Diet using the KIDMED score) were further collected. The mean age was 12±0.7 and about 24% were overweight and obese. An inverse correlation between total sleep time and body mass index (β =-0.829, P=0.021), fat mass (β =-0.526, P=0.025), and waist circumference (β =-0.426, P=0.045) was found. Similar results were found for weekdays sleep time, while an inverse relationship was found with PDSS score. Adherence to Mediterranean Diet was higher in under/normal weight adolescent with a significant linear association between the KIDMED score and the PDSS, weekdays sleep time and total sleep time. Sleep duration was also associated positively with fruits and vegetable intake and negatively with sweet and snack consumption and eating outside habits. Short sleep duration and poor sleep were associated with an increase in BMI and fat mass as well as to unhealthy eating behaviors. These findings suggest that sleep patterns could be a potential target for obesity prevention programs in young adolescence.
Keywords: Adolescents, Sleep, Obesity, KIDMED, PDSS, BMI
A growing body of evidence has delineated the predominant role of humoral mediators of inflammation in linking sleep with immunity. Nonetheless, characterization of the relationship between complement components with inflammatory functions and objective sleep measures has not been performed. In this study we investigated the relationships between objective measures of sleep and complement components with inflammatory functions. Thirty-six healthy male university students (age, 23.94±4.23 years; BMI, 23.44±2.67 kg/m2) completed the study. An RMS Quest 32 polysomnograph (PSG) was used for sleep recording. Non-fasting blood was collected before subjects went to bed on the second night in the sleep laboratory to estimate complement component 3 (C-3), complement component 4 (C-4), complement factor-H (Factor-H), C1-inhibitor (C1INH), complement factor I (CFI) and other inflammatory mediators, such as IL-6 and sICAM-1. Multiple linear regression analysis was used to assess the association between PSG sleep measures and inflammatory mediators. Higher values of C-3 and lower values of sICAM-1, C1INH, and CFI (adjusted model, R2 = 0.211, p < 0.041) predicted longer sleep duration. Lower C-3 (adjusted model, R2=0.078, p < 0.055) predicted higher N1 (%). Higher levels of C1INH and CFI and lower values of C-4 (model adjusted R2=0.269, p < 0.008) predicted higher N3 (%). Higher C-3, higher C-4, lower IL-6, lower C1INH and lower CFI (model adjusted R2=0.296, p < 0.007) predicted higher REM (%). Poor sleep measures were associated with increased levels of pro-inflammatory complement components and decreased anti-inflammatory complement components.
Keywords: Sleep, Inflammation, Complement component, Inflammatory mediators, Cytokine, Polysomnography