| 1. |
- Axelsson, John, 1969-
(author)
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Long shifts, short rests and vulnerability to shift work
- 2005
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Doctoral thesis (other academic/artistic)abstract
- At the same time as many urban economies are developing into 24-hour societies it is becoming increasingly popular amongst shift workers to compress their working hours. This is done by working longer shifts (>8h) and/or restricting free time (<16h) in between shifts – the main reasons are to gain longer bouts of free time and extra free weekends. However, there is a limited knowledge of the effects of such arrangements on sleep and wakefulness. Thus, the main purposes of the present thesis were to evaluate the effects of long working hours (in the form of 12h shifts) and short recovery periods. Another aim was to evaluate possible mechanisms that could suggest why some individuals develop problems with shift work while others do not.We used a combination of methods - sleep diaries, wake diaries, blood samples and objective measures of sleep and cognitive performance - across whole or large parts of shift schedules to evaluate acute effects of particularly demanding working periods, as well as the total effects of a shift cycle. Study I evaluated the effect of changing from an 8h- to a 12h-shift system. Study II evaluated the effects of long shifts in a shift schedule with both 8h- and 12h-shifts. Study III evaluated the effects of several consecutive short recovery periods (8-9h of recovery) and whether satisfaction with ones’ work hours was associated to problems with sleep and sleepiness. Study IV evaluated whether endocrinological markers of catabolic (cortisol) and anabolic (testosterone) activity changed across a shift sequence and whether satisfaction were related to them. Study V was a laboratory simulation of the effects of a short recovery period (4h of sleep) and whether a short nap could counteract any detrimental effects.There was no convincing evidence for 12h shifts inducing more problems with sleep and sleepiness than 8h shifts. With regard to recovery time between shifts, the shortest recovery times (only 8h) seriously shortened sleep duration and increased sleepiness, while 12h of recovery (between two consecutive 12h shifts) was judged as having no or limited effects on acute measures. The problems with the shortest recovery periods were worse in a schedule with several consecutive shifts and less pronounced in a schedule with few consecutive shifts. With regard to individual differences, it was found that subjects being dissatisfied with their working hours were vulnerable to short recovery periods, which was evident by less sufficient sleep and an accumulation of sleepiness across work periods with limited recovery time. Interestingly, these problems disappeared when they were allowed to recover after the work period. In addition, dissatisfied male shift workers had lower testosterone levels at the end of work periods, indicating disturbed anabolic activity. The simulated quick return supported that curtailed sleep affected sleepiness and performance and that a short nap could counteract these effects temporarily.It is concluded that long shifts (up to 12h) may be acceptable, whereas short recovery time (8h or less) is not. Most of the problems with short recovery periods were related to short sleep and sleepiness, and there is, clearly, a subgroup of workers that suffer more from this than others. It is argued that insufficient sleep and low testosterone levels (in males) might be key factors for developing shift intolerance, mainly by reducing the capacity to recover from shift work.
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| 2. |
- Balter, Leonie J. T., et al.
(author)
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Intelligence predicts better cognitive performance after normal sleep but larger vulnerability to sleep deprivation
- 2023
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In: Journal of Sleep Research. - : John Wiley & Sons. - 0962-1105 .- 1365-2869. ; 32:4
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Journal article (peer-reviewed)abstract
- Fluid intelligence is seen as a beneficial attribute, protecting against stress and ill-health. Whether intelligence provides resilience to the cognitive effects of insufficient sleep was tested in the current pre-registered experimental study. Participants (N = 182) completed the Raven's test (measuring fluid intelligence) and a normal night of sleep or a night of total sleep deprivation. Sleepiness and four cognitive tests were completed at 22:30 hours (baseline), and the following day after sleep manipulation. At baseline, higher fluid intelligence was associated with faster and more accurate arithmetic calculations, and better episodic memory, but not with spatial working memory, simple attention or sleepiness. Those with higher fluid intelligence were more, not less, impacted by sleep deprivation, evident for arithmetic ability, episodic memory and spatial working memory. We need to establish a more nuanced picture of the benefits of intelligence, where intelligence is not related to cognitive advantages in all situations.
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| 3. |
- Balter, Leonie J. T., et al.
(author)
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Sleep and subjective age : protect your sleep if you want to feel young
- 2024
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In: Proceedings of the Royal Society of London. Biological Sciences. - 0962-8452 .- 1471-2954. ; 291:2019
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Journal article (peer-reviewed)abstract
- The current studies examined the impact of insufficient sleep and sleepiness on the subjective experience of age. Study 1, a cross-sectional study of 429 participants (282 females (66%), 144 males, 3 other gender; age range 18-70), showed that for each additional day of insufficient sleep in the last 30 days, subjective age increased by 0.23 years. Study 2, an experimental crossover sleep restriction study (n = 186; 102 females (55%), 84 males; age range 18-46), showed that two nights of sleep restriction (4 h in bed per night) made people feel 4.44 years older compared to sleep saturation (9 h in bed per night). Additionally, moving from feeling extremely alert (Karolinska Sleepiness Scale (KSS) score of 1) to feeling extremely sleepy (KSS score of 9) was associated with feeling 10 years older in both studies. These findings provide compelling support for insufficient sleep and sleepiness to exert a substantial influence on how old we feel, and that safeguarding sleep is probably a key factor in feeling young.
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| 4. |
- Esfahani, Mahdad Jafarzadeh, et al.
(author)
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Validation of the sleep EEG headband ZMax
- 2023
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In: bioRxiv. - : Cold Spring Harbor Laboratory Press (CSHL). - 2692-8205.
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Journal article (other academic/artistic)abstract
- Polysomnography (PSG) is the gold standard for recording sleep. However, the standard PSG systems are bulky, expensive, and often confined to lab environments. These systems are also time-consuming in electrode placement and sleep scoring. Such limitations render standard PSG systems less suitable for large-scale or longitudinal studies of sleep. Recent advances in electronics and artificial intelligence enabled ‘wearable’ PSG systems. Here, we present a study aimed at validating the performance of ZMax, a widely-used wearable PSG that includes frontal electroencephalography (EEG) and actigraphy but no submental electromyography (EMG). We analyzed 135 nights with simultaneous ZMax and standard PSG recordings amounting to over 900 hours from four different datasets, and evaluated the performance of the headband’s proprietary automatic sleep scoring (ZLab) alongside our open-source algorithm (DreamentoScorer) in comparison with human sleep scoring. ZLab and DreamentoScorer compared to human scorers with moderate and substantial agreement and Cohen’s kappa scores of 59.61% and 72.18%, respectively. We further analyzed the competence of these algorithms in determining sleep assessment metrics, as well as shedding more lights on the bandpower computation, and morphological analysis of sleep microstructural features between ZMax and standard PSG. Relative bandpower computed by ZMax implied an error of 5.5% (delta), 4.5% (theta), 1.6% (alpha), 0.5% (sigma), 0.8% (beta), and 0.2% (gamma), compared to standard PSG. In addition, the microstructural features detected in ZMax did not represent exactly the same characteristics as in standard PSG. Besides similarities and discrepancies between ZMax and standard PSG, we measured and discussed the technology acceptance rate, feasibility of data collection with ZMax, and highlighted essential factors for utilizing ZMax as a reliable tool for both monitoring and modulating sleep.
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| 5. |
- Hansson, Lina S., 1986-, et al.
(author)
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Pointing out sickness : Detection of sickness from gait patterns
- 2021
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In: Brain, behavior, and immunity. - : Elsevier BV. - 0889-1591 .- 1090-2139. ; 98, s. 21-21
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Journal article (other academic/artistic)abstract
- Background: The ability to detect sick individuals is crucial for survival, by allowing avoidance of contagion. We have shown that humans can detect sick individuals from facial cues and body odors, but perception of these cues requires close proximity to the infectious person. Given that gait patterns can be detected from a distance and are altered during sickness, it would be beneficial to detect sickness from biological motion. Methods: We collected videos and point-light displays of walking individuals who were either made sick experimentally with an injection of lipopolysaccharide, or who were healthy (placebo). In study 1, 106 naive subjects watched these displays and rated them as coming from someone sick or healthy. In study 2, 106 other subjects rated health, sadness and tiredness of the displays on a VAS scale. Results: In Study 1, the sensitivity was 59% for videos and 57% for point-light displays, while the specificity was 74% for videos and 61% for point-light displays. Additional results will be presented at the conference. Conclusion: This study will indicate if sickness can be detected from gait patterns, possibly adding to immune defensive behaviors by facilitating avoidance of contagious peers.
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| 6. |
- Hansson, Lina S., et al.
(author)
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The walking sick : Perception of experimental sickness from biological motion
- 2023
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In: Brain, behavior, and immunity. - : Elsevier. - 0889-1591 .- 1090-2139. ; 113, s. 319-327
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Journal article (peer-reviewed)abstract
- Identification of sick conspecifics allows for avoidance of infectious threats, and is therefore an important behavioral defense against diseases. Here, we investigated if humans can identify sick individuals solely from biological motion and posture (using point-light displays). Additionally, we sought to determine which movements and sickness parameters would predict such detection. We collected video clips and derived point-light displays (one stride presented in a loop) of sick walkers (injected with lipopolysaccharide at 2.0 ng/kg body weight) and the same walkers when healthy (injected with saline). We then presented these displays to two groups, one group classified each walker as sick or healthy (study 1, n = 106), and the other group scored the walkers’ health on a visual analogue scale (study 2, n = 106). The raters were able to identify sick individuals above chance, and rated sick walkers as having worse health, both from observing video clips and point-light displays. Furthermore, both sickness detection and worse apparent health were predicted by inflammation-induced increase in rigidity and slower walking, but not other cues. Altogether, these findings indicate that biological motion can serve as a sickness cue, possibly allowing humans to identify sick conspecifics from a distance, and thereby allowing for disease avoidance.
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| 7. |
- Hansson, Lina S., 1986-, et al.
(author)
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The walking sick : what predicts the detection of walking sick individuals?
- 2022
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In: Brain, behavior, and immunity. - : Elsevier. - 0889-1591 .- 1090-2139. ; 106, s. 36-36
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Journal article (other academic/artistic)abstract
- Methods: In two studies, raters watched video recordings and point-light displays (i.e. dots depicting the body joints) of walking individuals who were either experimentally sick (after injection with lipopolysaccharide at 2.0 ng/kg bw) or healthy (after a placebo injection). In study 1, 106 raters classified each walking individual as either sick or healthy. In study 2, 106 other raters graded health of the stimuli on a visual analogue scale. We assessed the predicting effect on sickness detection (study 1) and apparent health (study 2) of walking parameters (objective measures of stride length, width, time, as well as knee angle, arm angle, and head angle) and well-known sickness responses (Sickness Questionnaire score, pain intensity, body temperature, and interleukin-6 concentration).Results: In study 1, shorter steps was the only predictor of the detection of sick individuals from video recordings (β=0.712(0.257), p=0.02). In the point-light displays, slower, wider, stiffer and shorter steps, all predicted a better sickness detection (β=0.0003(0.0001)-0.415(0.126), p<0.05).In study 2, lipopolysaccharide-induced slower, shorter and stiffer steps (B=5.214(1.888)-6.385(2.083), p<0.01), as well as higher interleukin-6 concentrations (B=0.051(0.020), p=0.01), predicted worse health ratings of sick individuals in the video recordings. In the point-light displays, lipopolysaccharide-induced slower, shorter and stiffer steps, and more head tilting, predicted worse health ratings of sick individuals (B=4.185(1.892)-6.701(2.092), p<0.05).Conclusions: The results imply that specific changes in walking parameters may aid in sickness detection, possibly regulating approach-avoidance behaviors towards sick peers.
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| 8. |
- Lasselin, Julie, 1986-, et al.
(author)
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Inflammation-related gait- Analysis of biological motion using the Microsoft® Kinect® during experimentally-induced sickness
- 2017
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In: Brain, behavior, and immunity. - : Elsevier BV. - 0889-1591 .- 1090-2139. ; 66
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Journal article (peer-reviewed)abstract
- Biological motion is a powerful communication cue and we have recently shown that sickness can be detected from gait pattern. However, it is unclear which gait characteristics are modulated by health status and whether change in gait pattern relates to inflammation and to the degree of sickness. The current study aimed at answering these questions by assessing biological motion characteristics in 19 individuals during experimentally-induced sickness, obtained by intravenous injection of lipopolysaccharide (2 ng/kg bw), and after placebo administration. Joint 3-D coordinates were recorded using the Microsoft® Kinect® during a walking paradigm and a mobility test (time-up-and-go test). Results indicate that gait during experimentally-induced sickness is characterized by slower and shorter strides, resulting in slower walking speed, as well as a slower time to stand up from a chair. In addition, sick subjects appear to swing their arms and to lift their legs less than when healthy, as reflected by smaller elbow angle during arm extension and larger knee angle during leg flexion compared to the placebo condition. Alterations in the overall gait pattern during experimentally-induced sickness was associated with interleukin-6 peak concentrations and a trend was observed with sickness symptoms. Altogether, these findings suggest that gait pattern might signal sickness/inflammatory status and could be used as an objective assessment of sickness, as well as to determine evolution of health status in individuals over time.
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| 9. |
- Thomsson, Kristina A, 1969, et al.
(author)
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Intestinal mucins from cystic fibrosis mice show increased fucosylation due to an induced Fucalpha1-2 glycosyltransferase.
- 2002
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In: The Biochemical journal. - 0264-6021. ; 367:Pt 3, s. 609-16
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Journal article (peer-reviewed)abstract
- In gene-targeted mouse models for cystic fibrosis (CF), the disease is mainly manifested by mucus obstruction in the intestine. To explore the mucus composition, mucins insoluble and soluble in 6 M guanidinium chloride were purified by three rounds of isopycnic ultracentrifugation from the small and large intestines of CF mice (Cftr(m1UNC)/Cftr(m1UNC)) and compared with wild-type mice. The amino acid composition was typical of that for mucins and showed increased amounts of the insoluble (2.5-fold increase) and soluble (7-fold increase) mucins in the small intestine of the CF mice compared with wild-type mice. Mucins from the large intestine of both wild-type and CF mice showed a high but constant level of fucosylation. In contrast, the insoluble and soluble mucins of the small intestine in CF mice revealed a large increase in fucose, whereas those of wild-type mice contained only small amounts of fucose. This increased fucosylation was analysed by releasing the O-linked oligosaccharides followed by GC-MS. NMR spectroscopy revealed that the increased fucosylation was due to an increased expression of blood group H epitopes (Fucalpha1-2Gal-). Northern-blot analysis, using a probe for the murine Fucalpha1-2 fucosyltransferase (Fut2), showed an up-regulation of this mRNA in the small intestine of the CF mice, suggesting that this enzyme is responsible for the observed increase in blood group H-type glycosylation. The reason for this up-regulation could be a direct or indirect effect of a non-functional CF transmembrane conductance regulator (CFTR) caused by the absence of CFTR channel.
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| 10. |
- Tognetti, Arnaud, et al.
(author)
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Discriminating between sick and healthy faces based on early sickness cues : an exploratory analysis of sex differences
- 2023
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In: Evolution, Medicine, and Public Health. - : Oxford University Press. - 2050-6201. ; 11:1, s. 386-396
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Journal article (peer-reviewed)abstract
- Background and objectives: It has been argued that sex and disease-related traits should influence how observers respond to sensory sickness cues. In fact, there is evidence that humans can detect sensory cues related to infection in others, but lack of power from earlier studies prevents any firm conclusion regarding whether perception of sickness cues is associated with sex and disease-related personality traits. Here, we tested whether women (relative to men), individuals with poorer self-reported health, and who are more sensitive to disgust, vulnerable to disease, and concerned about their health, overestimate the presence of, and/or are better at detecting sickness cues.Methodology: In a large online study, 343 women and 340 men were instructed to identify the sick faces from a series of sick and healthy photographs of volunteers with an induced acute experimental inflammation. Participants also completed several disease-related questionnaires.Results: While both men and women could discriminate between sick and healthy individuals above chance level, exploratory analyses revealed that women outperformed men in accuracy and speed of discrimination. Furthermore, we demonstrated that higher disgust sensitivity to body odors is associated with a more liberal decision criterion for categorizing faces as sick.Conclusion: Our findings give strong support for the human ability to discriminate between sick and healthy individuals based on early facial cues of sickness and suggest that women are significantly, although only slightly, better at this task. If this finding is replicated, future studies should determine whether women’s better performance is related to increased avoidance of sick individuals.
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