Search

Sleep-wake behavior, as well as sleepiness, is regulated by the joint action of an exponentially increasing drive for sleep--sleep homeostasis--and by variations in sleep propensity due to a biological circadian oscillator. However, large inter-individual differences remain. Short and long sleepers have been known to differ in the amount of homeostatic sleep pressure: long sleepers report higher levels of subjective sleepiness after sleep deprivation, whereas short sleepers exhibit no significant increase in sleepiness. The circadian pacemaker's program might be at the origin of the variability in habitual sleep duration in long and short sleepers. Previous studies within our group showed that the dynamics of both processes are similar in experienced sleepiness as in judged sleepiness. The aim of the present investigation was to determine whether habitual short, long and midrange sleepers exhibit similar integration patterns or whether the biological underpinnings of habitual sleep time variability emerge when judging sleepiness. Our results show an additive integration rule for homeostatic and circadian determinants of daytime sleepiness in all groups. However, rescaled functional values (RSFVs) and relative range indices (RRIs) suggest that short sleepers seem to tolerate higher levels of homeostatic sleep pressure in comparison to long sleepers and that in long sleepers, circadian variability plays a less prominent role in functional daytime sleepiness. As sleep-wake behavior is governed by both physiological mechanisms and psychological processes influenced by past experiences related to sleep and wake, these results have implications for sleep-wake-related health and safety. (Contains 5 figures, 5 tables, and 2 footnotes.)

Belgium has one of the highest numbers of COVID-19 cases per 1 million inhabitants. The pandemic has led to significant societal changes with repercussions on sleep and on mental health. We aimed to investigate the effect of the first and the second wave of COVID-19 on the sleep of the Belgian populationWe launched two online questionnaires, one during the first lockdown (7240 respondents) and one during the second (3240 respondents), to test differences in self-reported clinical insomnia (as measured by the Insomnia Severity Index) and sleep habits during the two lockdowns in comparison with the pre-COVID period. The number of persons with clinical insomnia rose during the first lockdown (19.22%) and further during the second (28.91%) in comparison with pre-lockdown (7.04-7.66%). Bed and rise times were delayed and there was an increased time in bed and sleep onset latency. There was further a decrease in total sleep time and in sleep efficiency during both confinements. The prevalence of clinical insomnia quadrupled during the second wave in comparison with the pre-lockdown situation. Sleep habits were most altered in the younger population, indicating a greater risk for this group to develop a sleep-wake rhythm disorder. [ABSTRACT FROM AUTHOR]

Limited scientific evidence suggests that physical activity is directly related to cognitive performance in patients with chronic fatigue syndrome (CFS). To date, no other study has examined the direct relationship between cognitive performance and physical fitness in these patients. This study examined whether cognitive performance and physical fitness are associated in female patients with CFS and investigated the association between cognitive performance and physical activity level (PAL) in the same study sample. We hypothesized that patients who performed better on cognitive tasks would show increased PALs and better performance on physical tests. The study included 31 women with CFS and 13 healthy inactive women. Participants first completed three cognitive tests. Afterward, they undertook a test to determine their maximal handgrip strength, performed a bicycle ergometer test, and were provided with an activity monitor. In patients with CFS, lower peak oxygen uptake and peak heart rate were associated with slower psychomotor speed (p < 0.05). Maximal handgrip strength was correlated with working memory performance (p < 0.05). Both choice and simple reaction time were lower in patients with CFS relative to healthy controls (p < 0.05 and p < 0.001, respectively). In conclusion, physical fitness, but not PAL, is associated with cognitive performance in female patients with CFS. [ABSTRACT FROM AUTHOR]

This study explores the relationship between tonal synchrony and maternal-infant social engagement based on free-play recordings of 15 mothers and their 3-month-old infants in a laboratory setting. Moment-by-moment analyses on a microlevel were used to study social engagement and vocal interaction. We analysed and categorized 854 vocalization periods (mother-only vocalizations, tonal interaction periods, nontonal interaction periods, and mutual silence). Tonal synchrony was analysed in terms of harmonic and pentatonic series based on pitch frequency analyses. Social engagement was microanalyzed in terms of matched and mismatched engagement states. ANOVA-repeated measures revealed, most importantly, a significant relationship between TIPs and social interaction repair, which indicates the importance of tonal synchrony in the flow of social engagement in mother-infant dyads. Other significant relationships were found between (a) nTIPs/mismatch-mismatch, and, (b) MOV/affect loss. As mentioned in the discussion, the findings are suggestive for clinical applications (e.g., music therapy) and warrant further research. [ABSTRACT FROM AUTHOR]

Introduction: In 2018, the Belgian Defence introduced a commercial off-the-shelf dive computer (Shearwater Perdix™) for use by its military divers. There were operational constraints when using its default gradient factors (GF). We aimed to provide guidelines for optimal GF selection., Methods: The Defence and Civil Institute of Environmental Medicine (DCIEM) dive tables and the United States Navy (USN) air decompression tables are considered acceptably safe by the Belgian Navy Diving Unit. The decompression model used in the Shearwater Perdix (Bühlmann ZH-L16C algorithm with GF) was programmed in Python. Using a sequential search of the parameter space, the GF settings were optimised to produce decompression schedules as close as possible to those prescribed by the USN and DCIEM tables., Results: All reference profiles are approached when GF LO is kept equal to 100 and only GF HI is reduced to a minimum of 75 to prolong shallower stop times. Using the Perdix default settings (GF LO = 30 and GF HI = 70) yields deeper initial stops, leading to increased supersaturation of the 'slower' tissues, which potentially leads to an increased DCS risk. However, Perdix software does not currently allow for the selection of our calculated optimal settings (by convention GF LO < GF HI ). A sub-optimal solution would be a symmetrical GF setting between 75/75 and 95/95., Conclusions: For non-repetitive air dives, the optimal GF setting is GF LO 100, with only the GF HI parameter lowered to increase safety. No evidence was found that using the default GF setting (30/70) would lead to a safer decompression for air dives as deep as 60 metres of seawater; rather the opposite. Belgian Navy divers have been advised against using the default GF settings of the Shearwater Perdix dive computer and instead adopt symmetrical GF settings which is currently the optimal achievable approach considering the software constraints., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

This study reports a cross-cultural comparison of the vocal pitch patterns of 15 Mexican Spanish-speaking and 15 Belgian Flemish-speaking dyads, recorded during 5min of free-play in a laboratory setting. Both cultures have a tradition of dyadic face-to-face interaction but differ in language origins (i.e., Romanic versus Germanic). In total, 374 Mexican and 558 Flemish vocal exchanges were identified, analyzed and compared for their incidence of tonal synchrony (harmonic/pentatonic series), non-tonal synchrony (with/without imitations) and pitch and/or interval imitations. The main findings revealed that dyads in both cultures rely on tonal synchrony using similar pitch ratios and timing patterns. However, there were significant differences in the infants' vocal pitch imitation behavior. Additional video-analyzes on the contingency patterns involved in pitch imitation showed a cross-cultural difference in the maternal selective reinforcement of pitch imitation. The results are interpreted with regard to linguistic, developmental and cultural aspects and the 'musilanguage' model., (Copyright © 2015 Elsevier Inc. All rights reserved.)