| 1. |
- Balter, Leonie J. T., et al.
(author)
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Experimental Sleep Deprivation Results in Diminished Perceptual Stability Independently of Psychosis Proneness
- 2022
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In: Brain Sciences. - : MDPI AG. - 2076-3425. ; 12:10
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Journal article (peer-reviewed)abstract
- Psychotic disorders as well as psychosis proneness in the general population have been associated with perceptual instability, suggesting weakened predictive processing. Sleep disturbances play a prominent role in psychosis and schizophrenia, but it is unclear whether perceptual stability diminishes with sleep deprivation, and whether the effects of sleep deprivation differ as a function of psychosis proneness. In the current study, we aimed to clarify this matter. In this preregistered study, 146 participants successfully completed an intermittent version of the random dot kinematogram (RDK) task and the 21-item Peters Delusion Inventory (PDI-21) to assess perceptual stability and psychosis proneness, respectively. Participants were randomized to sleep either as normal (8 to 9 h in bed) (n = 72; Mage = 24.7, SD = 6.2, 41 women) or to stay awake through the night (n = 74; Mage = 24.8, SD = 5.1, 44 women). Sleep deprivation resulted in diminished perceptual stability, as well as in decreases in perceptual stability over the course of the task. However, we did not observe any association between perceptual stability and PDI-21 scores, nor a tendency for individuals with higher PDI-21 scores to be more vulnerable to sleep-deprivation-induced decreases in perceptual stability. The present study suggests a compromised predictive processing system in the brain after sleep deprivation, but variation in psychosis trait is not related to greater vulnerability to sleep deprivation in our dataset. Further studies in risk groups and patients with psychosis are needed to evaluate whether sleep loss plays a role in the occurrence of objectively measured perceptual-related clinical symptoms.
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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. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- Härdelin, Goran, et al.
(author)
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Do Mothers Have Worse Sleep Than Fathers? Sleep Imbalance, Parental Stress, and Relationship Satisfaction in Working Parents
- 2021
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In: Nature and Science of Sleep. - 1179-1608. ; 13, s. 1955-1966
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Journal article (peer-reviewed)abstract
- Purpose: Previous research indicates that mothers take a larger responsibility for child care during the night and that they have more disturbed sleep than fathers. The purpose of this study was to determine whether such a sleep imbalance exists in working parents of young children, and the extent to which it depends on the way sleep is measured. The study also examined whether imbalanced sleep between parents predicts parental stress and relationship satisfaction.Methods: Sleep was measured for seven consecutive days in 60 parenting couples (average age of the youngest child: 3.3 years ± SD 2.5 years). Actigraphs were worn across the week, and ratings of sleep, parental stress, and relationship satisfaction were made daily.Results: Mothers perceived their sleep quality as worse (b= − 0.38 scale units, p< 0.001), with more wake periods (b= +0.96 awakenings, p< 0.001) but with longer sleep duration (b= +32.4 min, p< 0.01) than fathers. Actigraphy data confirmed that mothers slept longer than fathers (b= +28.03 min, p< 0.001), but no significant differences were found for wake time, number of awakenings or who woke up first during shared awakenings. Furthermore, there was no difference in whether mothers and fathers slept sufficiently. The level of sleep imbalance between parents did not predict parental stress. A larger imbalance in subjective sleep sufficiency predicted decreased relationship satisfaction for fathers (b= − 0.13 scale units, p< 0.01) but increased relationship satisfaction for mothers (b= 0.14 scale units, p< 0.05). No other sleep imbalance measures predicted relationship satisfaction.Conclusion: Our findings are in line with previous research on sleep in men and women in general, with longer sleep and subjective reports of sleep disturbances in women, rather than previous research on sleep in parents of young children. Thus, we found no evidence of a sleep imbalance when both parents have similar working responsibilities.
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| 8. |
- Sundelin, Tina, 1982-, et al.
(author)
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Is snoozing losing? Why intermittent morning alarms are used and how they affect sleep, cognition, cortisol, and mood
- 2024
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In: Journal of Sleep Research. - 0962-1105 .- 1365-2869. ; 33:3
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Journal article (peer-reviewed)abstract
- Pressing the snooze button is a common way to start the day, but little is known about this behaviour. Through two studies we determined predictors and effects of snoozing. In Study 1 (n = 1732) respondents described their waking habits, confirming that snoozing is widespread, especially in younger individuals and later chronotypes. Morning drowsiness and shorter sleep were also more common for those who snooze. Study 2 was a within-subjects laboratory study (with polysomnography) on habitual snoozers (n = 31), showing that 30 min of snoozing improved or did not affect performance on cognitive tests directly upon rising compared to an abrupt awakening. Bayes factors indicate varying strengths of this evidence. Snoozing resulted in about 6 min of lost sleep, while preventing awakenings from slow-wave sleep (N3). There were no clear effects of snoozing on the cortisol awakening response, morning sleepiness, mood, or overnight sleep architecture. A brief snooze period may thus help alleviate sleep inertia, without substantially disturbing sleep, for late chronotypes and those with morning drowsiness.
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| 9. |
- Sundelin, Tina, 1982-
(author)
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The Face of Sleep Loss
- 2015
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Doctoral thesis (other academic/artistic)abstract
- Sleep deprivation has been studied for over a century, providing knowledge about the benefits of sleep for many physiological, cognitive, and behavioural functions. However, there have only been anecdotal indications about what a tired or sleep-deprived person looks like, despite the fact that appearance influences not only how other people perceive a person but also how they evaluate them and behave towards them. How someone with sleep loss is perceived and evaluated by others is the focus of this thesis. Facial photographs of 48 participants were taken after normal sleep and after either one night of total sleep deprivation or two nights of partial sleep deprivation. The photographs were then evaluated in four different studies by a total of 288 raters recruited from universities and the general public in Stockholm, Sweden. The faces were rated on attractiveness, health, tiredness, sleepiness, sociability, trustworthiness, employability, and leadership ability. These factors were all adversely affected by sleep loss. Furthermore, looking tired was strongly related to being less attractive, looking less healthy and less trustworthy, and being perceived as a poorer employee and leader. One of the studies assessed facial features commonly associated with looking tired, showing that sleep deprivation results in eyes which appear more swollen and red, with dark circles and hanging eyelids, as well as paler skin with more fine lines and wrinkles. When sleep deprived, people were also perceived as more sad. In conclusion, the four studies show that sleep loss and a tired appearance affect how one is perceived by other people. These perceptions may lead to negative evaluations in interpersonal situations, both personal and professional. This thesis thus demonstrates social benefits of prioritizing sleep, adding to the physiological, cognitive, and behavioural research on sleep loss.
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| 10. |
- Sundelin, Tina, 1982-, et al.
(author)
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Trait Anxiety Does Not Predict the Anxiogenic Response to Sleep Deprivation
- 2022
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In: Frontiers in Behavioral Neuroscience. - : Frontiers Media SA. - 1662-5153. ; 16
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Journal article (peer-reviewed)abstract
- Sleep deprivation has in several studies been found to increase anxiety. However, the extent to which this anxiogenic effect depends on one's underlying trait anxiety has not previously been determined. Using two separate sleep-loss experiments, the current research investigated whether trait anxiety (STAI-T) moderates the increase in state anxiety (STAI-S) following one night of total sleep loss (study 1, N = 182, age 25.3 ± 6.5, 103 women) and two nights of partial sleep restriction (study 2, N = 67, age 26.5 ± 7.4, 38 women). Both studies showed the expected anxiogenic effect of sleep loss, and a clear relationship between trait anxiety and state anxiety. However, the anxiogenic effect of sleep loss was not moderated by trait anxiety, as there was an equal impact regardless of trait anxiety level. These findings indicate that, although sleep loss is related to general anxiety as well as anxiety disorders, for a non-clinical sample the anxiogenic effect of short-term sleep loss is not affected by baseline levels of anxiety.
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