Our research team at the Stress Research Institute aims to increase the knowledge and awareness of how sleep in the modern life affects our biology, cognition and health. Some of the research questions we pursue include:

- How sleep loss affects the brain and why some are more vulnarable than others?

- How fast can you start trust an awakening brain?

- How do parents to young children sleep and what can be done to support them?

- Can more sleep speed up recovery from infections?

A selection from Stockholm University publication database

• 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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• Fysisk aktivitet vid insomni

  2021. Göran Kecklund, John Axelsson. FYSS 2021, 363-368

  Chapter

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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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• 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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• 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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• Sleep during naturally occurring respiratory infections

  2019. Julie Lasselin (et al.). Brain, behavior, and immunity 79, 236-243

  Article

  There is strong experimental support that infections increase the drive for sleep in animals, and it is widely believed that more sleep is part of an adaptive immune response. While respiratory infections (RI) are very prevalent in humans, there is a striking lack of systematic knowledge on how it affects sleep. We recruited 100 people, among whom 28 became sick with an RI during the study period (fulfilling criteria for influenza-like illness, ILI, or acute respiratory infection, ARI). We measured sick participants' sleep at home, both objectively (actigraphy) and subjectively (diary ratings), for one week as well as four weeks later when healthy. During the week with RI, people spent objectively longer time in bed and had a longer total sleep time compared to the healthy week. During the infection, participants also had more awakenings, but no significant differences in sleep latency or sleep efficiency. While sick, people also reported increased difficulties falling asleep, worse sleep quality, more restless sleep and more shallow sleep, while they did not report sleep to be less sufficient. Most problems occurred at the beginning of the sickness week, when symptoms were strong, and showed signs of recovery thereafter (as indicated by interactions between condition and day/night of data collection for all the 10 sleep outcomes). The degree of symptoms of RI was related to a worse sleep quality and more restless sleep, but not to any of the objective sleep outcomes or the other subjective sleep variables. Having a higher body temperature was not significantly related to any of the sleep variables. This study suggests that having a respiratory infection is associated with spending more time in bed and sleeping longer, but also with more disturbed sleep, both objectively and subjectively. This novel study should be seen as being of pilot character. There is a need for larger studies which classify pathogen type and include baseline predictors, or that manipulate sleep, in order to understand whether the sleep alterations seen during infections are adaptive and whether sleep interventions could be used to improve recovery from respiratory infections.

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• Identification of acutely sick people and facial cues of sickness

  2018. John Axelsson (et al.). Proceedings of the Royal Society of London. Biological Sciences 285 (1870)

  Article

  Detection and avoidance of sick individuals have been proposed as essential components in a behavioural defence against disease, limiting the risk of contamination. However, almost no knowledge exists on whether humans can detect sick individuals, and if so by what cues. Here, we demonstrate that untrained people can identify sick individuals above chance level by looking at facial photos taken 2 h after injection with a bacterial stimulus inducing an immune response (2.0 ng kg-1 lipopolysaccharide) or placebo, the global sensitivity index being d' = 0.405. Signal detection analysis (receiver operating characteristic curve area) showed an area of 0.62 (95% confidence intervals 0.60-0.63). Acutely sick people were rated by naive observers as having paler lips and skin, a more swollen face, droopier corners of the mouth, more hanging eyelids, redder eyes, and less glossy and patchy skin, as well as appearing more tired. Our findings suggest that facial cues associated with the skin, mouth and eyes can aid in the detection of acutely sick and potentially contagious people.

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• Circadian Entrainment to the Natural Light-Dark Cycle across Seasons and the Weekend

  2017. Ellen R. Stothard (et al.). Current Biology 27 (4), 508-513

  Article

  Reduced exposure to daytime sunlight and increased exposure to electrical lighting at night leads to late circadian and sleep timing [1-3]. We have previously shown that exposure to a natural summer 14 hr 40 min:9 hr 20 min light-dark cycle entrains the human circadian clock to solar time, such that the internal biological night begins near sunset and ends near sunrise [1]. Here we show that the beginning of the biological night and sleep occur earlier after a week's exposure to a natural winter 9 hr 20 min:14 hr 40 min light-dark cycle as compared to the modern electrical lighting environment. Further, we find that the human circadian clock is sensitive to seasonal changes in the natural light-dark cycle, showing an expansion of the biological night in winter compared to summer, akin to that seen in non-humans [4-8]. We also show that circadian and sleep timing occur earlier after spending a weekend camping in a summer 14 hr 39 min:9 hr 21 min natural light-dark cycle compared to a typical weekend in the modern environment. Weekend exposure to natural light was sufficient to achieve similar to 69% of the shift in circadian timing we previously reported after a week's exposure to natural light [1]. These findings provide evidence that the human circadian clock adapts to seasonal changes in the natural light-dark cycle and is timed later in the modern environment in both winter and summer. Further, we demonstrate that earlier circadian timing can be rapidly achieved through natural light exposure during a weekend spent camping.

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• Multimodal Emotion Recognition Is Resilient to Insufficient Sleep

  2017. Benjamin C. Holding (et al.). Sleep 40 (11)

  Article

  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.

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• Health consequences of shift work and insufficient sleep

  2016. Göran Kecklund, John Axelsson. BMJ. British Medical Journal 355

  Article

  This review summarises the literature on shift work and its relation to insufficient sleep, chronic diseases, and accidents. It is based on 38 meta-analyses and 24 systematic reviews, with additional narrative reviews and articles used for outlining possible mechanisms by which shift work may cause accidents and adverse health. Evidence shows that the effect of shift work on sleep mainly concerns acute sleep loss in connection with night shifts and early morning shifts. A link also exists between shift work and accidents, type 2 diabetes (relative risk range 1.09-1.40), weight gain, coronary heart disease (relative risk 1.23), stroke (relative risk 1.05), and cancer (relative risk range 1.01-1.32), although the original studies showed mixed results. The relations of shift work to cardiometabolic diseases and accidents mimic those with insufficient sleep. Laboratory studies indicate that cardiometabolic stress and cognitive impairments are increased by shift work, as well as by sleep loss. Given that the health and safety consequences of shift work and insufficient sleep are very similar, they are likely to share common mechanisms. However, additional research is needed to determine whether insufficient sleep is a causal pathway for the adverse health effects associated with shift work.

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Show all publications by John Axelsson at Stockholm University