After receiving my PhD from Stockholm University in 2015, focusing on social perceptions of sleep loss (Thesis: The Face of Sleep Loss), I started a postdoc at Karolinska Institutet to study social interactions during sleep deprivation. In 2016, I received an International Postdoc Grant from the Swedish Research Council (VR) to work with Dr. Tessa West at New York University. During this postdoc visit, I focused on physiological measures such as heart rate variability and sympathetic nervous system acitivty in addition to behavioural and dyadic tasks following sleep loss.

Since 2019, I am employed as an Assistant Professor at Stockholm University. In my current research I integrate lab-based experimental studies with field-based research, to answer various questions regarding sleep, social interactions, and wellbeing.

Visit my Google Scholar page for an up-to-date publication list.

A selection from Stockholm University publication database

• Is snoozing losing? Why intermittent morning alarms are used and how they affect sleep, cognition, cortisol, and mood

  2023. Tina Sundelin, Shane Landry, John Axelsson. Journal of Sleep Research

  Article

  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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• Experimental Sleep Deprivation Results in Diminished Perceptual Stability Independently of Psychosis Proneness

  2022. Leonie J. T. Balter (et al.). Brain Sciences 12 (10)

  Article

  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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• Intelligence predicts better cognitive performance after normal sleep but larger vulnerability to sleep deprivation

  2022. Leonie J. T. Balter (et al.). Journal of Sleep Research

  Article

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• Trait Anxiety Does Not Predict the Anxiogenic Response to Sleep Deprivation

  2022. Tina Sundelin, Benjamin C. Holding. Frontiers in Behavioral Neuroscience 16

  Article

  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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• Deep Learning for Identification of Acute Illness and Facial Cues of Illness

  2021. Castela Forte (et al.). Frontiers in Medicine 8

  Article

  Background: The inclusion of facial and bodily cues (clinical gestalt) in machine learning (ML) models improves the assessment of patients' health status, as shown in genetic syndromes and acute coronary syndrome. It is unknown if the inclusion of clinical gestalt improves ML-based classification of acutely ill patients. As in previous research in ML analysis of medical images, simulated or augmented data may be used to assess the usability of clinical gestalt.

  Objective: To assess whether a deep learning algorithm trained on a dataset of simulated and augmented facial photographs reflecting acutely ill patients can distinguish between healthy and LPS-infused, acutely ill individuals.

  Methods: Photographs from twenty-six volunteers whose facial features were manipulated to resemble a state of acute illness were used to extract features of illness and generate a synthetic dataset of acutely ill photographs, using a neural transfer convolutional neural network (NT-CNN) for data augmentation. Then, four distinct CNNs were trained on different parts of the facial photographs and concatenated into one final, stacked CNN which classified individuals as healthy or acutely ill. Finally, the stacked CNN was validated in an external dataset of volunteers injected with lipopolysaccharide (LPS).

  Results: In the external validation set, the four individual feature models distinguished acutely ill patients with sensitivities ranging from 10.5% (95% CI, 1.3-33.1% for the skin model) to 89.4% (66.9-98.7%, for the nose model). Specificity ranged from 42.1% (20.3-66.5%) for the nose model and 94.7% (73.9-99.9%) for skin. The stacked model combining all four facial features achieved an area under the receiver characteristic operating curve (AUROC) of 0.67 (0.62-0.71) and distinguished acutely ill patients with a sensitivity of 100% (82.35-100.00%) and specificity of 42.11% (20.25-66.50%).

  Conclusion: A deep learning algorithm trained on a synthetic, augmented dataset of facial photographs distinguished between healthy and simulated acutely ill individuals, demonstrating that synthetically generated data can be used to develop algorithms for health conditions in which large datasets are difficult to obtain. These results support the potential of facial feature analysis algorithms to support the diagnosis of acute illness.

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• Do Mothers Have Worse Sleep Than Fathers? Sleep Imbalance, Parental Stress, and Relationship Satisfaction in Working Parents

  2021. Goran Härdelin (et al.). Nature and Science of Sleep 13, 1955-1966

  Article

  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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• Human sickness detection is not dependent on cultural experience

  2021. Artin Arshamian (et al.). Proceedings of the Royal Society of London. Biological Sciences 288 (1954)

  Article

  Animals across phyla can detect early cues of infection in conspecifics, thereby reducing the risk of contamination. It is unknown, however, if humans can detect cues of sickness in people belonging to communities with whom they have limited or no experience. To test this, we presented Western faces photographed 2 h after the experimental induction of an acute immune response to one Western and five non-Western communities, including small-scale hunter-gatherer and large urban-dwelling communities. All communities could detect sick individuals. There were group differences in performance but Western participants, who observed faces from their own community, were not systematically better than all non-Western participants. At odds with the common belief that sickness detection of an out-group member should be biased to err on the side of caution, the majority of non-Western communities were unbiased. Our results show that subtle cues of a general immune response are recognized across cultures and may aid in detecting infectious threats.

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• Quantifying Cognitive Impairment After Sleep Deprivation at Different Times of Day

  2021. Benjamin C. Holding (et al.). Frontiers in Behavioral Neuroscience 15

  Article

  Cognitive functioning is known to be impaired following sleep deprivation and to fluctuate depending on the time of day. However, most methods of assessing cognitive performance remain impractical for environments outside of the lab. This study investigated whether 2-min smartphone-based versions of commonly used cognitive tests could be used to assess the effects of sleep deprivation and time of day on diverse cognitive functions. After three nights of normal sleep, participants (N = 182) were randomised to either one night of sleep deprivation or a fourth night of normal sleep. Using the Karolinska WakeApp (KWA), participants completed a battery of 2-min cognitive tests, including measures of attention, arithmetic ability, episodic memory, working memory, and a Stroop test for cognitive conflict and behavioural adjustment. A baseline measurement was completed at 22:30 h, followed by three measurements the following day at approximately 08:00 h, 12:30 h, and 16:30 h. Sleep deprivation led to performance impairments in attention, arithmetic ability, episodic memory, and working memory. No effect of sleep deprivation was observed in the Stroop test. There were variations in attention and arithmetic test performance across different times of day. The effect of sleep deprivation on all cognitive tests was also found to vary at different times of day. In conclusion, this study shows that the KWA's 2-min cognitive tests can be used to detect cognitive impairments following sleep deprivation, and fluctuations in cognitive performance relating to time of day. The results demonstrate the potential of using brief smartphone-based tasks to measure a variety of cognitive abilities within sleep and fatigue research.

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• Sickness and sleep health predict frustration and affective responses to a frustrating trigger

  2021. Leonie J. T. Balter, Tina Sundelin, John Axelsson. Scientific Reports 11 (1)

  Article

  Fluctuations in health and sleep are common, but we know surprisingly little about how these daily life stressors affect one's level of frustration and sensitivity to becoming frustrated. In this pre-registered study, 517 participants (M_age = 30.4, SD = 10.4) reported their current sickness symptoms, health status, sleepiness, and sleep duration and quality the previous night. They also rated their general frustration and mood before and after a mild frustration-eliciting task. In the task, participants were instructed to copy geometric shapes onto a piece of paper, without lifting the pen from the paper. Participants were given three minutes to copy the eight shapes, but in order to induce frustration half of them were unsolvable. The study was subsequently repeated in an independent sample (N = 113). Frustration increased in response to the task; however, those with the worst sickness symptoms or sleep health reduced or did not change their frustration levels. Instead, across both studies, frustration was already high at baseline for these individuals. These findings indicate that being sick or having poor sleep is related to high general frustration, but resilience to further frustration due to mild frustrating situations.

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• Vulnerability in Executive Functions to Sleep Deprivation Is Predicted by Subclinical Attention-Deficit/Hyperactivity Disorder Symptoms

  2021. Orestis Floros (et al.). Biological Psychiatry 6 (3), 290-298

  Article

  Background: Sleep loss results in state instability of cognitive functioning. It is not known whether this effect is more expressed when there is an increased cognitive demand. Moreover, while vulnerability to sleep loss varies substantially among individuals, it is not known why some people are more affected than others. We hypothesized that top-down regulation was specifically affected by sleep loss and that subclinical inattention and emotional instability traits, related to attention-deficit/hyperactivity disorder symptoms, predict this vulnerability in executive function and emotion regulation, respectively.

  Methods: Healthy subjects (ages 17–45 years) rated trait inattention and emotional instability before being randomized to either a night of normal sleep (n = 86) or total sleep deprivation (n = 87). Thereafter, they performed a neutral and emotional computerized Stroop task, involving words and faces. Performance was characterized primarily by cognitive conflict reaction time and reaction time variability (RTV), mirroring conflict cost in top-down regulation.

  Results: Sleep loss led to increased cognitive conflict RTV. Moreover, a higher level of inattention predicted increased cognitive conflict RTV in the neutral Stroop task after sleep deprivation (r = .30, p = .0055) but not after normal sleep (r = .055, p = .65; interaction effect β = 6.19, p = .065). This association remained after controlling for cognitive conflict reaction time and emotional instability, suggesting domain specificity. Correspondingly, emotional instability predicted cognitive conflict RTV for the emotional Stroop task only after sleep deprivation, although this effect was nonsignificant after correcting for multiple comparisons.

  Conclusions: Our findings suggest that sleep deprivation affects cognitive conflict variability and that less stable performance in executive functioning may surface after sleep loss in vulnerable individuals characterized by subclinical symptoms of inattention.

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• Effects of sleep loss and attention on negotiations

  2020. Tina Sundelin, Tessa West, John Axelsson. Journal of Sleep Research, 104-104

  Conference

  Objectives/Introduction: Although there is a growing interest in the effect of sleep loss on social behaviors, little is known about actual social interactions following sleep deprivation. Many social exchanges involve some kind of negotiation, ranging from discussing one′s salary with a supervisor to deciding who will prepare dinner in a household. As sleep‐deprived individuals have a shorter attention span, decreased executive functions, and are more emotional, we hypothesized that sleep loss would lead to worse negotiation abilities. We also predicted that this would be mediated by decreased attention.

  Methods: In the first study, 182 participants were randomised to one night of total sleep loss or normal sleep. The following day, they performed a 15‐minute dyadic collaborative task, where they negotiated for the best possible outcome for the dyad. In the second study, 106 participants were randomised to two nights of 4 h sleep per night or two nights of 8 h sleep per night, after which they performed a 6‐minute dyadic negotiation task where the dyad partners had opposing goals. Prior to the negotiation tasks, participants performed a short psychomotor vigilance task.

  Results: Although sleep loss affected reaction time on the PVT (p < 0.001 and p = 0.02, respectively), and longer reaction times predicted worse negotiation outcomes in the opposing‐goals task (p = 0.009), there was no effect of sleep loss on negotiation outcome in either study (p = 0.37 and p = 0.66, respectively). Reaction times did not predict negotiation outcomes in the collaborative task (p = 0.95).

  Conclusions: Sleep loss does lead to decreased attention, which is useful for negotiation ability, but despite this, there was consistently no effect of insufficient sleep on negotiation outcomes in two large studies. Potentially, negative effects of sleep loss would be more prominent in longer negotiation settings, where lapses in attention may be more frequent.

  Disclosure: Nothing to disclose.

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• People expressing olfactory and visual cues of disease are less liked

  2020. Georgia Sarolidou (et al.). Philosophical Transactions of the Royal Society of London. Biological Sciences 375 (1800)

  Article

  For humans, like other social animals, behaviour acts as a first line of defence against pathogens. A key component is the ability to detect subtle perceptual cues of sick conspecifics. The present study assessed the effects of endotoxin-induced olfactory and visual sickness cues on liking, as well as potential involved mechanisms. Seventy-seven participants were exposed to sick and healthy facial pictures and body odours from the same individual in a 2 x 2 factorial design while disgust-related facial electromyography (EMG) was recorded. Following exposure, participants rated their liking of the person presented. In another session, participants also answered questionnaires on perceived vulnerability to disease, disgust sensitivity and health anxiety. Lower ratings of liking were linked to both facial and body odour disease cues as main effects. Disgust, as measured by EMG, did not seem to be the mediating mechanism, but participants who perceived themselves as more prone to disgust, and as more vulnerable to disease, liked presented persons less irrespectively of their health status. Concluding, olfactory and visual sickness cues that appear already a few hours after the experimental induction of systemic inflammation have implications for human sociality and may as such be a part of a behavioural defence against disease. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'.

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• Sleepiness as motivation

  2020. John Axelsson (et al.). Sleep 43 (6)

  Article

  STUDY OBJECTIVES: To determine how sleepiness and sleep deprivation drive the motivation to engage in different behaviors.

  METHODS: We studied the sleepiness of 123 participants who had been randomized to sleep deprivation or normal sleep, and their willingness to engage in a range of everyday behaviors.

  RESULTS: Self-reported sleepiness was a strong predictor of the motivation to engage in sleep-preparatory behaviors such as shutting one's eyes (OR=2.78, 95%CI: 2.19-3.52 for each step up on the Karolinska Sleepiness Scale) and resting (OR=3.20, CI: 2.46-4.16). Sleepiness was also related to the desire to be cared for by a loved one (OR=1.49, CI: 1.22-1.82), and preparedness to utilize monetary and energy resources to get to sleep. Conversely, increased sleepiness was associated with a decreased motivation for social and physical activities (e.g., be with friends OR=0.71, CI: 0.61-0.82; exercise OR=0.65, CI: 0.56-0.76). Sleep deprivation had similar effects as sleepiness on these behaviors. Neither sleepiness nor sleep deprivation had strong associations with hunger, thirst, or food preferences.

  CONCLUSIONS: Our findings indicate that sleepiness is a dynamic motivational drive that promotes sleep-preparatory behaviors and competes with other drives and desired outcomes. Consequently, sleepiness may be a central mechanism by which impaired alertness, e.g., due to insufficient sleep, contributes to poor quality of life and adverse health. We propose that sleepiness helps organize behaviors toward the specific goal of assuring sufficient sleep, in competition with other needs and incentives. A theoretical framework on sleepiness and its behavioral consequences are likely to improve our understanding of several disease mechanisms.

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• Sleepiness, sleep duration, and human social activity

  2020. Benjamin C. Holding (et al.). Proceedings of the National Academy of Sciences of the United States of America 117 (35), 21209-21217

  Article

  Daytime sleepiness impairs cognitive ability, but recent evidence suggests it is also an important driver of human motivation and behavior. We aimed to investigate the relationship between sleepiness and a behavior strongly associated with better health: social activity. We additionally aimed to investigate whether a key driver of sleepiness, sleep duration, had a similar relationship with social activity. For these questions, we considered bidirectionality, time of day, and differences between workdays and days off. Over 3 wk, 641 working adults logged their behavior every 30 min, completed a sleepiness scale every 3 h, and filled a sleep diary every morning (rendering >292,000 activity and >70,000 sleepiness datapoints). Using generalized additive mixed-effect models, we analyzed potential nonlinear relationships between sleepiness/sleep duration and social activity. Greater sleepiness predicted a substantial decrease in the probability of social activity (odds ratio 95% CI = 0.34 to 0.35 for days off), as well as a decreased duration of such activity when it did occur. These associations appear especially robust on days off and in the evenings. Social duration moderated the typical time-of-day pattern of sleepiness, with, for example, extended evening socializing associated with lower sleepiness. Sleep duration did not robustly predict next-day social activity. However, extensive social activity (>5 h) predicted up to 30 min shorter subsequent sleep duration. These results indicate that sleepiness is a strong predictor of voluntary decreases in social contact. It is possible that bouts of sleepiness lead to social withdrawal and loneliness, both risk factors for mental and physical ill health.

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• Biological motion during inflammation in humans

  2020. Julie Lasselin (et al.). Brain, behavior, and immunity 84, 147-153

  Article

  Biological motion is a powerful perceptual cue that can reveal important information about the inner state of an individual. Activation of inflammatory processes likely leads to changes in gait, posture, and mobility patterns, but the specific characteristics of inflammation-related biological motion have not been characterized. The aim of this study was to determine the effect of inflammation on gait and motion in humans. Systemic inflammation was induced in 19 healthy volunteers with an intravenous injection of lipopolysaccharide (2 ng/kg body weight). Biological motion parameters (walking speed, stride length and time, arm, leg, head, and shoulder angles) were assessed during a walking paradigm and the timed-up-and-go test. Cytokine concentrations, body temperature, and sickness symptoms were measured. During inflammation, compared to placebo, participants exhibited shorter, slower, and wider strides, less arm extension, less knee flexion, and a more downward-tilting head while walking. They were also slower and took a shorter First step in the timed-up-and-go test. Higher interleukin-6 concentrations, stronger sickness symptoms, and lower body temperature predicted the inflammation-related alterations in biological motion. These findings show that biological motion contains clear information about the inflammatory status of an individual, and may be used by peers or artificial intelligence to recognize that someone is sick or contagious.

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• Sleep and Social Impressions

  2019. Tina Sundelin, Benjamin C. Holding. Sleep, Personality, and Social Behavior, 119-133

  Chapter

  The impression you form of someone depends on your attention, motivations, and previous experiences, as well as that person’s appearance and actions. In other words, social perception, or how we perceive others, is a two-way street involving the person perceiving and the person being perceived. As sleep may play a role in both of these processes, this chapter looks at the effects of sleep on how you perceive other people as well as how you are perceived by them. With topics ranging from first impressions and emotion recognition to stereotyping and trust, we provide an overview of the current literature on sleep and social impressions, and discuss possibilities and potential pitfalls of future research in this area.

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