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PURPOSE. To examine the isolated and combined effects of severe hypoxia and a mild thermal challenge on performance, physiological measures, reaction time (RT) and serum brain derived neurotrophic factor (BDNF). METHODS. Nine trained male athletes (Age: 23±3y; Wmax: 332.6±45.0W; PL4) completed four experimental trials (CON: 15°C/0m, ALT: 15°C/3800m, TEMP: 25°C/0m, ALT+TEMP: 25°C/3800m) in a randomized, cross-over design. Subjects cycled for 30min in a self-paced test starting at 75%Wmax, their goal was to 'perform as much work as possible in 30min'. Power output (PO), heart rate, blood lactate, pulse oximetry and core and skin temperature were assessed. Before and after the time trial blood samples were taken for the analysis of BDNF and the psychomotor vigilance task was performed for the determination of RT and RT variability. Two-way (temperature x altitude) and three-way (temperature x altitude x time) ANOVA with repeated measures was used to examine main and interaction effects, paired t-tests were used to identify pair-wise differences. P0.05). CONCLUSION. Both stressors separately from each other significantly decreased exercise capacity, but we did not observe an interaction effect. Altitude induced an increase in RTand an increase in RT variability, presenting tentative evidence of mental fatigue after exercise in acute hypoxia. Exercise significantly increased BDNF, but no effect of altitude on the BDNF concentration was observed.* BR is funded by the FWO Fund for Scientific Research Flanders, Belgium.

Objectives. The current study was designed to investigate the influence of individual differences in the flexibility of the circadian rhythm on sleepiness, during 28 hours of sleep deprivation. Methods. Based on the flexibility of the circadian rhythm, as measured with the Circadian Type Inventory, 17 rigid (mean age 23 years, SD=4.9) and 17 flexible types (mean age 22 years, SD=4.5) were selected. These participants were deprived from sleep for 28 hours, in controlled laboratory conditions. Subjective and performance based sleepiness were determined during the sleep deprivation period by use of the Karolinska Sleepiness Scale (KSS; hourly measures) and the Psychomotor Vigilance Task (PVT; 2 hourly measures), with a focus on reaction speed (RS). Results. An increase in subjective and performance based sleepiness was observed under conditions of prolonged wakefulness (FKSS(5.476,164.285)=52.643, p

Mensen zijn dagdieren. Wie daar geen rekening mee houdt, zet zijn lichaam constant in stressmodus en loopt zo een hoger risico op tal van aandoeningen.

Last decennia the musical characteristics of mother-infant dialogues were regularly emphasized and recent research (Van Puyvelde et al., 2010, 2013) showed that specific tonal aspects are related with crucial social-affective micro-aspects of a dyadic interaction. During mother-infant bonding moments of affect repair, the observed interrelated pitch frequency ratios of their vocals show a similar pattern as present in a harmonic and pentatonic series with a strong incidence of consonant simple frequency ratios. In contrast, during moments of prolonged disengagement or increased arousal, their vocal pitches did not show this pattern and appeared to be primarily dissonant. Moreover, the amount of simple and complex frequency ratios in relation to a shared tonal center (F0 of the harmonic series) was in line with the hierarchical structure of harmonic series (i.e., 70% high consonance, 20% medium consonance and 5% low consonance or dissonance). In this study, we wanted to know whether tonal synchrony is related with physiological events on a dyadic level. An important developmental task of an infant is to require the capacity to self-regulate. On a physiological level, self-regulation has been regularly related with cardiac vagal control or respiratory sinus arrhythmia (RSA). Moreover RSA has become a well-used measure in infant research as it can be obtained in a non-invasive way by ECG-respiratory registration during experimental research (e.g., Feldman, 2006). RSA reflects a component of the natural heart rhythm variability (HRV), that is manifest during a respiration cycle as the result of the regulation of the autonomic nervous system, mediated by the parasympathetic branch, more specific the nervus vagus (Berntson et al., 1997). During inspiration, heart rate accelerates, whereas, during expiration, heart rate decelerates. The degree of RSA thus gives an indication of the vagal control of the heart (Berntson et al., 1997). RSA as a multiply determined physiological variable. Besides vagal outflow, RSA reflects, among others, respiratory and somatomotor metabolic parameters, such as movement and talking speech (Berntson et al., 2007). It was thus not possible to study a physiological-vocal coupling with regard to mother-infant dialogues. Therefore, we presented two musical fragments to mothers and their three-month old infants (tonal fragment based on the hierarchical order of a harmonic series versus atonal fragment without tonal structure). RSA was analyzed by means of peak-valley method and respiration corrected by means of within-subject analyses. Statistical analyses were conducted with a mixed effects model that included motor activity during the experiment as a covariate. Results showed increased infant RSA from baseline to tonal music and no significant difference between baseline and atonal music. In the mothergroup, only mothers that heard the difference between the tonal and non-tonal fragment and that hold their infant close to the body showed increased RSA during tonal music. Other mothers did not show significant differences. Results will be discussed in relation to the nature-nurture debate concerning the biological versus cultural roots of consonant and dissonant music, the need to include motor and respiratory components in cardiovascular infant research and maternal-infant socio-affective development.

In this longitudinal study, we examined the existence of a direct maternal-infant physiological relationship in the synchrony of respiratory sinus arrhythmia (RSA) between mothers and infants. RSA has regularly been related with infant self-regulation and has become a well-used measure in infant research as it can be obtained in a non-invasive way by ECG-respiratory registration during experimental research (e.g., Feldman, 2006). RSA reflects a component of the natural heart rhythm variability (HRV), that is manifest during a respiration cycle as the result of the regulation of the autonomic nervous system, mediated by the parasympathetic branch, more specific the nervus vagus (Berntson et al., 1997). During inspiration, heart rate accelerates, whereas, during expiration, heart rate decelerates. The degree of RSA thus gives an indication of the vagal control of the heart (Berntson et al., 1997). RSA as a multiply determined physiological variable. Besides vagal outflow, RSA reflects, among others, respiratoryand somatomotor metabolic parameters, such as movement and talking speech (Berntson et al., 2007). Therefore, inclusion of respiratory and movement components in analyses are needed. In the present study, we conducted paced breathing experiments with 11 mother-infant dyads when the infant was 1, 2, 4, 8 and 12 weeks old. We instructed mothers to breathe at 5 different rates (6-12-15-20-6 cycles per minute) with their infant lying on their body. Maternal-infant ECG and respiration were registered with simultaneous video recording. RR-interval (RRI), respiratory sinus arrhythmia (RSA) and respiration frequency (Fresp) were calculated. We analyzed mother-infant RSA response profiles, using an ANOVA approach followed by post-hoc testing of interaction terms. Polynomial and Helmert contrasts were used to evaluate respectively maternal-infant paced-breathing response differences and developmental differences. Results showed that a maternal-infant physiological relationship is manifest during the first two months of life. During this period, an infant is more susceptible to fluctuations in the RSA curves of their mother than on a later age. At the age of 3 months, maternal-infant differences in RSA were too large to determine a relationship. These results are in line with the 2-months developmental shift of social orientation. Results are discussed with regard to infants' vagal maturation and the need to include respiratory components in cardiovascular infant research.

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When evaluating sleepiness induced safety consequences it can be important to take into account inter-individual differences in the manifestation of sleepiness. Di Milia and colleague's [1] studied retrospective alertness in subjects with a flexible versus rigid circadian system. They found significant differences in alertness between flexible and rigid types between 04PM and 10PM. The current study explores the influence of individual differences in the flexibility of the circadian system on sleepiness profiles, in response to a lack of sleep. Fifteen participants enrolled in a 28 h total sleep deprivation study, of which 4 men and 11 women. Participants were selected on the basis of their circadian phenotype, assessed by the factor "Flexibility" of the Circadian Type Index (CTI) [1] and were divided in two groups: rigid types (CTI flexibility score 27, 75th percentile; mean age=22.25, SD=6.50). Inclusion criteria were:age between 18 and 39 years old, good physical health (SF-20) [2], [3], no psychiatric problems (MINI) [4], habitual sleep duration between 6,5 and 8,5 hours, good sleep quality (Pittsburg Sleep Quality Index; PSQI) [5], no excessive daytime sleepiness (Epworth Sleepiness Scale; ESS) [6], no extreme morning-evening types [7], no previous detrimental neuropsychiatric reactions to sleep deprivation, no shift work, no current medical treatment or use of medicines or drugs (excluding oral contraceptives) influencing sleep. The Karolinska Sleepiness Scale (KSS) [8], the Psychomotor Vigilance Task (PVT) [9] and the Alpha Attenuation test (AAT) [10], were used to asses subjective, performance based and physiological sleepiness. Results showed an increase of sleepiness under conditions of extended wakefulness. A sudden increase of sleepiness occurred when the biological night time started, with a rather stable level of sleepiness during the rest of the sleep deprivation period. Inter-individual differences in the behavioral flexibility of the circadian system were reflected in differential sleepiness profiles, suggesting that the circadian rhythm parameter of flexibility can be pivotal in evaluating sleepiness and sleepiness induced safety consequences. Flexible subjects displayed higher levels of sleepiness during the biological day, together with lower levels of subjective and performance based sleepiness during the biological night. In line with the previous results of Di Milia and colleague's [1] our findings suggest that the circadian rhythm parameter of flexibility may be an important factor in evaluating the tolerance to shift work and to other conditions associated with functioning during nighttime.

The present study introduces the concept of a mother-infant group therapy that makes use of music, singing and moving to establish maternal-infant intersubjectivity. It was conducted in a residential Mother-Baby Unit for mothers with postnatal depression and their infants over a five week period. Maternal-infant intersubjectivity of four dyads in relation to the group dynamics were micro-analyzed for Session 1 and 5. We made within-session (i.e., beginning-middle-end) and between-session (Session 1 versus Session 5) comparisons for the number of intersubjectivity moments (ISM), total time of intersubjectivity (IST) and the mean duration of ISMs on a dyadic (i.e., own mother/infant involved) and non-dyadic level (i.e., own mother/infant not involved). Additionally, three ISM-levels (degree of group contribution) were distinguished. The results indicated a significant increase of ISM/IST from Session 1 to 5. Within-session analyses showed that ISM/IST significantly decreased through Session 1 and remained stable throughout Session 5. Intersubjectivity occurred mainly on ISM-Level 1 during Session 1 and on ISM-Level 3 during Session 5, suggesting increased dyadic autonomy and self-efficacy. The results are discussed in relation to the musical characteristics of mother-infant dyads, music improvisation techniques, group processes and intersubjective development.

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Introduction: It is well known that people exhibit a circadian rhythm in a number of physiological and neurobehavioral functions. This endogenous rhythm can be described on the base of phase, amplitude and stability of the rhythm and trait-individual differences can be found in these circadian rhythm parameters. Phase measurements have drawn a lot of research attention, whereas little emphasis was placed on the other circadian rhythm parameters. Objectives: This study was draft up to further examine age, gender and shiftwork differences in regard to circadian rhythm parameters. Methods: Subjects: 1305 subjects filled in the online survey measuring circadian type parameters. The mean age of the total sample was 31 years (SD=13), with an age range of 12-90 years. Men made up 29% of the sample (N=337) and had a mean age of 33 years (SD=14), women made up 71% of the sample (N=928) and had a mean age of 32 years (SD=13). Of the total sample 10% (N=131) worked in shifts, of which 41% men (N=54) and 59% women (N=77). Measurements: Subjects were asked to complete five questionnaires online: the Circadian Type Inventory (CTI| Di Milia, Smith, & Folkard, P&ID, 2004), the Circadian Amplitude and Phase Scale (CAPS| Di Milia, Folkard, Hill, & Walker, CI, 2010), the Pittsburgh Sleep Quality Index (PSQI| Buysse, Reynolds, Monk, Berman, & Kupfer, PR, 1989), the Composite Scale of Morningness (CSM| Smith, Reilly, & Midkiff, JoAP, 1989), the Epworth Sleepiness Scale (ESS| Johns, S, 1991) in combination with additive questions about demographic characteristics. Here we will only focus on results regarding CTI and CAPS. Statistics: To look more closely into age, gender and shiftwork variations in circadian rhythm parameters MANOVA's were performed with circadian rhythm parameters as dependent variables, gender and shiftwork as fixed factors and age as covariate. Results: CTI Using Pillai's trace, there was a significant effect of the inter-individual variables of age (V = .086, F(2,1298) = 61.241, p Separate univariate ANOVA's revealed an age effect regarding circadian languidity, whereby younger age was associated with more languidity (F(1,1299) = 115.441, p CAPS The multivariate models for age (V = .047, F(3,1297) = 21.298, p An effect of age and gender was found on all parameters. Age was positively associated with morningness (F(1,1301) = 5.981, p Conclusion: Our results indicate a small but significant association between older age and morningness, strength of preference and time awareness. These variables are expected to reflect daytime impairment and the susceptibility to rhythm disturbances, which in turn are associated with increased age (Di Milia, Folkard, Hill & Walker, CI, 2010; Kerkhof, BP, 1985). In contrast, we found a decrease in languidity to be associated with an increase in age, however this association also remains rather modest. Gender effects in circadian rhythm parameters were found; men seem to show more flexibility of the circadian rhythm and a lower strength of preference. Both parameters can be associated with a more flexible circadian regulation. These findings corroborate with the finding that the circadian system is more flexible in men in comparison with women (Natale & Danese, BRR, 2002). Furthermore a difference in circadian flexibility was found between shift workers and non-shift workers. This finding may be explained by the self-selection effect often reported in shift work research, whereby more tolerant people start and stay engaged in shift work, in combination with the reported association between circadian flexibility and shift work tolerance (Knutsson & Åkerstedt, W&S, 1992; Di Milia, Smith & Folkard, P&ID, 2005).

Objectives: The aim of this study was to evaluate diurnal variation in positive and negative emotion and the impact of 28 hours of sleep deprivation on emotional experience. Methods: Subjects Young healthy sleepers (mean age 24y, SD = 6, preliminary N = 15) were selected for the purpose of this study. Materials and procedure After an adaptation and baseline night (8 hours time in bed), subjects were kept awake for 28 hours in controlled laboratory conditions. Affective dynamics were evaluated by 4 hourly assessment of the extended version of the Positive and Negative Affect Schedule (PANAS-X; Watson & Clark, 1994) with a focus on relevant emotion components, respectively Positive (PA) and Negative Affect (NA), the basic emotions of Fear, Hostility, Guilt, Sadness, Joviality, Self-Assurance and Attentiveness and the affective state of Fatigue. Analyses Repeated-measures analyses of variance (ANOVA) with time of day (from 10h day 1 to 10h day 2) as repeated measure were performed for the different emotion components. Contrasts were used to look more closely into significant time of day variations. Results: Preliminary results indicate a relative stable manifestation of general NA even after 28h of sleep deprivation, F(3.279,45.907) = 1.276, ns. For PA a significant variability was observer over time, F(6,78) = 19.323, p Furthermore a general decrease in all basic positive emotions was found over the sleep deprivation period, respectively F Joviality(6,84) = 914.612, p Regarding the basic negative emotion scales, a general stability was found regarding the emotions of fear and guilt, respectively F Fear(3.455,48.374) = .728, ns and F Guilt(2.413,33.788) = .861, ns. A trend was found regarding hostility, F(2.085, 29.189) = 2.485, p Conclusion: In line with previous research, a diurnal stability of general negative affect was found. However the sharp rise in positive emotion from morning till noon, was not replicated in this study (Clark, Watson & Leeka, M&E, 1989). Yet, a clear effect of sleep deprivation on general positive affect was observed. Subjects showed a decrease in all basic positive emotions, starting in the early night period, with a stabilization throughout the further sleep deprivation period. Regarding the basic negative emotion components, the effect seems to be less determined. During the whole sleep deprivation period, an emotional stability has been observed for the basic emotions of guilt and surprisingly, against earlier evidence, of fear (Sagaspe et al., B&C, 2006). However, together with the expected night-time increase in fatigue (Durmer & Dinges, SiN, 2005), an evening rise in sadness and a night-time increase in hostility has been observed, all followed by a relative stability during the further sleep deprivation period. These results indicate a selective change in emotional experience instead of an overall change in affect with increasing sleep deprivation, an important finding to be further investigated with relevant societal and clinical implications.

Kelly Ickmans: Cognitive Impairment in Adults with Chronic Pain and/or Fatigue. Kelly holds a master of science degree and is physiotherapist and PhD researcher in the Pain in Motion research group (www.paininmotion.be), Vrije Universiteit Brussel, Belgium. Her research is focused on exercise and cognitive (dys) functioning in chronic pain patients. She has published 10 papers in peer reviewed international journals, the majority of which address chronic fatigue syndrome. The role that exercise and indices of physical status play with regard to cognitive (dys) function in this patient population will be discussed.

In this longitudinal study, we examined the existence of a direct maternal-infant physiological relationship in the synchrony of respiratory sinus arrhythmia (RSA) between mothers and infants. Paced breathing experiments were conducted with 11 mother-infant dyads when the infant was 1, 2, 4, 8 and 12 weeks old. We instructed mothers to breathe at 5 different rates (6-12-15-20-6 cycles per minute) with their infant lying on their body. Maternal-infant ECG and respiration were registered with simultaneous video recording. RR-interval (RRI), respiratory sinus arrhythmia (RSA) and respiration frequency (Fresp) were calculated. Results revealed maternal-infant physiological synchrony during the first two months of life -peaking at two months- and disappearing by three months of age with following significant predictive relationships: maternal-infant Fresp/RSA, Fresp/RRI, RSA/RSA and RRI/RRI. Discussion addresses vagal maturation, self-regulation and the 2-months developmental shift of social orientation. Additionally, the need to include the respiratory component in mother-infant cardiovascular studies is highlighted.

Objectives: The overall adverse effect on sleep and performance of being exposed to constant darkness and in isolated and confined environments (ICE), is fairly undisputed. However, reports show evidence of individuals with stable or even increased performance during Antarctic winter-over campaigns. The purpose of this study is to assess the stability and the composite nature of the inter-individual differences in psychomotor performance in a sample of Antarctic over-winterers. Methods: 13 male volunteers (36.7+/-9.4 yrs) from the Concordia Research Station performed a 10-min psychomotor vigilance task every 6 weeks during the 2011 Antarctic winter. The stability of the inter-individual differences was quantified by intra-class correlation (ICC). Outcomes showing substantial or perfect stability (ICC>.60) were subjected to a functional principal component analysis (fPCA). Results: Z-adjusted mean response speed shows the largest ICC (.612), suggesting a substantial stability in inter-individual variability. 77.8% of the individual variance in response speed profiles is accounted for by two functional components. The first functional component explains 57.15% of the variance and characterizes the individual variability from the mean response speed function. High (low) scores on the first component raise (lower) the mean response speed profile. The second functional component explains 20.6% of the variance and is characterized by a downward functional trend over time. Individuals scoring high (low) on the second component show a more decreasing (increasing) trend in response speed profiles in comparison to the mean response speed function. Conclusion: Most of the variability in response speed profiles is accounted for by stable inter-individual differences in mean reaction speed, irrespective from any state-dependent decline during the winter-over period. An additional proportion of the variability is explained by differences in the rate of decline/improvement of response speed. It is suggested thatthis component reflects the adaptive capacity of the individual to conditions of isolation and confinement under constant natural darkness.

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Objectives: Subjective sleepiness is likely the organism's first indication of the detrimental effects of prolonging wakefulness. As individuals largely differ in their vulnerability to sleep loss, accounting for individual differences in subjective sleepiness is of crucial importance when considering safety critical operations. The purpose of this study is to precisely quantify the determinants of inter-individual variability in daytime sleepiness to capture its phenotypic richness. Methods: 23 volunteers (11 females; M age=30.41, SD= 10.26) enrolled in a 36hr constant routine. Sleepiness was assessed 2-hourly by means of VASs and of the Karolinska Drowsiness Test. Circadian rhythmicity was assessed through salivary cortisol. Subjective sleepiness data were subjected to a functional principal component analysis (fPCA). Results: Approximately 80% of the total variance is accounted for by three functional components: component S (50.28%), component C (18.40%) and component D (10.09%). High (low) scores oncomponent S raise (lower) the mean sleepiness profile. Individuals with high (low) scores on component C display more (less) rhythmic variability in their sleepiness profiles, as characterized by a higher (lower) peak-to-through amplitude. Participants with high (low) scores on component D show higher (lower) than average levels of subjective sleepiness during morning hours and a buildup of wake effort occurring later (earlier) than low (high) scorers. Component S scores were related to self-reported habitual sleep times (r= .58, p

Objectives: The purpose of this study is to assess if individual differences in baseline subjective alertness profiles are predictive of vigilance decrements during consecutive sleep restriction. Methods: 29 healthy women (age=43.4+/-15.9; BMI=22.7+/-2.2; ESS=6.66+/-3.2; PQSI=3.69+/-1.8) underwent a full PSG before three consecutive nights of sleep restriction (4hrs TIB). Baseline subjective alertness was assessed day 1 at 7:30AM and from 9AM 2-hourly until 1AM by means of the Stanford Sleepiness Scale (SSS). SSS data were smoothed using 4th order B-splines with 5 equidistant interior knots. Smoothed profiles were subjected to a functional principal component analysis in order to assess the composite nature of the individual variability of alertness profiles. Psychomotor vigilance was assessed by means of the PVT every day at 9AM and 1PM and at 5 PM at baseline and after 3 days of sleep restriction. Results: 96.1% of the individual variance in baseline subjective alertness profiles is accounted for by 3 functional components. The first functional component explains 78.3% of the variance and lowers or increases the mean function without altering its form. Component 1 scores were significantly related to perceived sleep quality (PSQI; r=.39, pConclusion: Although most of the variance in individual profiles is accounted for by tonic differences, subtle rhythmic differences in baseline alertness related to the proportion of SWS predict the speed of vigilance decline during consecutive sleep restriction.