Tina Sundelin

Beauty sleep: experimental study on the perceived health and attractiveness of sleep deprived people

Objective To investigate whether sleep deprived people are perceived as less healthy, less attractive, and more tired than after a normal night’s sleep. Design Experimental study. Setting Sleep laboratory in Stockholm, Sweden. Participants 23 healthy, sleep deprived adults (age 18-31) who were photographed and 65 untrained observers (age 18-61) who rated the photographs. Intervention Participants were photographed after a normal night’s sleep (eight hours) and after sleep deprivation (31 hours of wakefulness after a night of reduced sleep). The photographs were presented in a randomised order and rated by untrained observers. Main outcome measure Difference in observer ratings of perceived health, attractiveness, and tiredness between sleep deprived and well rested participants using a visual analogue scale (100 mm). Results Sleep deprived people were rated as less healthy (visual analogue scale scores, mean 63 (SE 2) v 68 (SE 2), P<0.001), more tired (53 (SE 3) v 44 (SE 3), P<0.001), and less attractive (38 (SE 2) v 40 (SE 2), P<0.001) than after a normal night’s sleep. The decrease in rated health was associated with ratings of increased tiredness and decreased attractiveness. Conclusion Our findings show that sleep deprived people appear less healthy, less attractive, and more tired compared with when they are well rested. This suggests that humans are sensitive to sleep related facial cues, with potential implications for social and clinical judgments and behaviour. Studies are warranted for understanding how these effects may affect clinical decision making and can add knowledge with direct implications in a medical context.

Cues of fatigue: effects of sleep deprivation on facial appearance.

STUDY OBJECTIVE To investigate the facial cues by which one recognizes that someone is sleep deprived versus not sleep deprived. DESIGN Experimental laboratory study. SETTING Karolinska Institutet, Stockholm, Sweden. PARTICIPANTS Forty observers (20 women, mean age 25 ± 5 y) rated 20 facial photographs with respect to fatigue, 10 facial cues, and sadness. The stimulus material consisted of 10 individuals (five women) photographed at 14:30 after normal sleep and after 31 h of sleep deprivation following a night with 5 h of sleep. MEASUREMENTS Ratings of fatigue, fatigue-related cues, and sadness in facial photographs. RESULTS The faces of sleep deprived individuals were perceived as having more hanging eyelids, redder eyes, more swollen eyes, darker circles under the eyes, paler skin, more wrinkles/fine lines, and more droopy corners of the mouth (effects ranging from b = +3 ± 1 to b = +15 ± 1 mm on 100-mm visual analog scales, P < 0.01). The ratings of fatigue were related to glazed eyes and to all the cues affected by sleep deprivation (P < 0.01). Ratings of rash/eczema or tense lips were not significantly affected by sleep deprivation, nor associated with judgements of fatigue. In addition, sleep-deprived individuals looked sadder than after normal sleep, and sadness was related to looking fatigued (P < 0.01). CONCLUSIONS The results show that sleep deprivation affects features relating to the eyes, mouth, and skin, and that these features function as cues of sleep loss to other people. Because these facial regions are important in the communication between humans, facial cues of sleep deprivation and fatigue may carry social consequences for the sleep deprived individual in everyday life.

Behavioral and neural correlates to multisensory detection of sick humans

Significance In the perpetual race between evolving organisms and pathogens, the human immune system has evolved to reduce the harm of infections. As part of such a system, avoidance of contagious individuals would increase biological fitness. The present study shows that we can detect both facial and olfactory cues of sickness in others just hours after experimental activation of their immune system. The study further demonstrates that multisensory integration of these olfactory and visual sickness cues is a crucial mechanism for how we detect and socially evaluate sick individuals. Thus, by motivating the avoidance of sick conspecifics, olfactory–visual cues, both in isolation and integrated, may be important parts of circuits handling imminent threats of contagion. Throughout human evolution, infectious diseases have been a primary cause of death. Detection of subtle cues indicating sickness and avoidance of sick conspecifics would therefore be an adaptive way of coping with an environment fraught with pathogens. This study determines how humans perceive and integrate early cues of sickness in conspecifics sampled just hours after the induction of immune system activation, and the underlying neural mechanisms for this detection. In a double-blind placebo-controlled crossover design, the immune system in 22 sample donors was transiently activated with an endotoxin injection [lipopolysaccharide (LPS)]. Facial photographs and body odor samples were taken from the same donors when “sick” (LPS-injected) and when “healthy” (saline-injected) and subsequently were presented to a separate group of participants (n = 30) who rated their liking of the presented person during fMRI scanning. Faces were less socially desirable when sick, and sick body odors tended to lower liking of the faces. Sickness status presented by odor and facial photograph resulted in increased neural activation of odor- and face-perception networks, respectively. A superadditive effect of olfactory–visual integration of sickness cues was found in the intraparietal sulcus, which was functionally connected to core areas of multisensory integration in the superior temporal sulcus and orbitofrontal cortex. Taken together, the results outline a disease-avoidance model in which neural mechanisms involved in the detection of disease cues and multisensory integration are vital parts.

Role of Inflammation in Human Fatigue: Relevance of Multidimensional Assessments and Potential Neuronal Mechanisms

Fatigue is a highly disabling symptom in various medical conditions. While inflammation has been suggested as a potential contributor to the development of fatigue, underlying mechanisms remain poorly understood. In this review, we propose that a better assessment of central fatigue, taking into account its multidimensional features, could help elucidate the role and mechanisms of inflammation in fatigue development. A description of the features of central fatigue is provided, and the current evidence describing the association between inflammation and fatigue in various medical conditions is reviewed. Additionally, the effect of inflammation on specific neuronal processes that may be involved in distinct fatigue dimensions is described. We suggest that the multidimensional aspects of fatigue should be assessed in future studies of inflammation-induced fatigue and that this would benefit the development of effective therapeutic interventions.

Multimodal Emotion Recognition Is Resilient to Insufficient Sleep: Results From Cross-Sectional and Experimental Studies

Objectives Insufficient sleep has been associated with impaired recognition of facial emotions. However, previous studies have found inconsistent results, potentially stemming from the type of static picture task used. We therefore examined whether insufficient sleep was associated with decreased emotion recognition ability in two separate studies using a dynamic multimodal task. Methods Study 1 used a cross-sectional design consisting of 291 participants with questionnaire measures assessing sleep duration and self-reported sleep quality for the previous night. Study 2 used an experimental design involving 181 participants where individuals were quasi-randomized into either a sleep-deprivation (N = 90) or a sleep-control (N = 91) condition. All participants from both studies were tested on the same forced-choice multimodal test of emotion recognition to assess the accuracy of emotion categorization. Results Sleep duration, self-reported sleep quality (study 1), and sleep deprivation (study 2) did not predict overall emotion recognition accuracy or speed. Similarly, the responses to each of the twelve emotions tested showed no evidence of impaired recognition ability, apart from one positive association suggesting that greater self-reported sleep quality could predict more accurate recognition of disgust (study 1). Conclusions The studies presented here involve considerably larger samples than previous studies and the results support the null hypotheses. Therefore, we suggest that the ability to accurately categorize the emotions of others is not associated with short-term sleep duration or sleep quality and is resilient to acute periods of insufficient sleep.

How can we improve identification of contagious individuals? Factors influencing sickness detection

The comment by Kurvers and Wolf [1] on our recent publication [2] highlights some urgent questions that emerge not only in the wake of our study, but also in relation to the developing field of how behavioural mechanisms have evolved to defend against microbial infections. Their additional analyses of our data show that, even though there were small individual differences in the ability to discriminate between healthy and sick individuals (although some expert raters were identified), there were substantial differences in response bias, that is, how individuals balance the trade-off between sensitivity and specificity. Kurvers and Wolf also focus on how social-learning strategies could influence the detection of disease cues, and thereby disease dynamics, in the population in relation to the social network position of the ‘detector’. Thus, how do individuals differ in their ability to discriminate between sick and healthy peers, and in what way can social information—learning from others—influence ones responses to potentially sick people? There are good reasons …

Total sleep deprivation does not impact emotioncategorisation in dynamic stimuli

INTRODUCTION: Post Traumatic Stress Disorder (PTSD) is a significant health problem with as key symptoms aversive memory intrusions and overgeneralization of the traumatic event, as well as sleep disturbances. Interestingly, sleep has an important role in memory consolidation. In particular, sleep spindles in different cortical areas reflect reprocessing and consolidation of specific memory traces. Given their strong relationship with memory reprocessing during sleep and reported memory and sleep alterations in PTSD, sleep spindles may play a role in the aetiology of PTSD. The current study assesses sigma fluctuations in PTSD patients. METHODS: Several parameters of sigma fluctuations were analysed and compared between traumatized police officers and combat veterans with (N=13) and without (N=14) PTSD. An automated detection method, free of a-priori assumptions regarding spindle characteristic, was used to obtain an unbiased representation of all sigma fluctuations. The standard deviation of the filtered sleep EEG (11-16 Hz) was computed (moving window: 0.2s), and all waxing/waning couplets with an amplitude over 5 microvolt were detected. For each detected sigma fluctuation, several variables were computed (e.g. duration, amplitude etc). RESULTS: Increased spindling activity was found in PTSD patients compared to trauma controls. This despite SSRI use in a small subsample of patients, which decreased spindling. The assumption free analyses revealed details regarding spindle abnormalities in PTSD that would have been missed by analysing only heuristically detected spindles. CONCLUSION: The spindle abnormalities in PTSD may reflect excessive reprocessing and consolidation of trauma-related memories and may in this way contribute to the emotional memory problems. memory problems.Objectives: The ratio between day and night varies across the year and its annual amplitude increases with latitude. As a result, seasonal variation, which operates over the very slow time-scale of months, in temperature and food availability, increases with latitude. We can thus expect latitudinal adaptation in major biological processes involving timing of reproduction, metabolic balance, circadian organization, and sensory adaptation. Methods: Here we will showcase latitudinal clines from different species to demonstrate evolutionary adaptation at different levels of organization. Results: Evolutionary selection force on timing of reproduction is usually very strong because it involves a primary fitness component. Photoperiodism driving the reproductive axis is under circadian control (near 24-h) and thus circadian properties like phase of entrainment and period are expected to be under strong selection pressure. Conclusions: Our data indicate latitudinal adaptation in circadian properties from insects and humans. Latitudinal variation may thus comprise is a powerful tool to investigate mechanisms underscoring circadian organization and photoperiodic responses and to unveil selective forces responsible for daily and seasonal adaptations.Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible.