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Andreas Gerhardsson Foto: Psykologiska institutionen/HD

Andreas Gerhardsson

Doktorand

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Arbetar vid Psykologiska institutionen
Telefon 08-16 38 34
E-post andreas.gerhardsson@psychology.su.se
Besöksadress Frescati hagväg 14
Rum 149
Postadress Psykologiska institutionen 106 91 Stockholm

Om mig

Jag tog min master i psykologi 2014 tillsammans med en lärarexamen. En artikel baserat på min masteruppsats publicerades året efter. Sedan min examen har jag arbetat som forskningsassistent på Stressforskningsinstitutet (SU) i ett projekt där vi undersökte hur sömnbrist påverkar responsen på akut social stress. Vi undersökte även hur andra kognitiva och emotionella funktioner påverkades av sömnbrist. 

Undervisning

Jag har sedan vårterminen 2017 börjat undervisa i statistik, hållt en föreläsning om sömn, lett laboration i kognitiv psykologi och handlett mindre studier.

Forskning

Jag är i allmänhet intresserad av experimentell psykologi och i huvudsak interaktionen mellan emotioner och kognition och hur den påverkas av sömnbrist. Det kommer vara huvudfokus i min avhandling.

Publikationer

I urval från Stockholms universitets publikationsdatabas
  • 2018. Johanna Schwarz (et al.). Psychoneuroendocrinology 96, 155-165

    Sleep loss and psychosocial stress often co-occur in today’s society, but there is limited knowledge on the combined effects. Therefore, this experimental study investigated whether one night of sleep deprivation affects the response to a psychosocial challenge. A second aim was to examine if older adults, who may be less affected by both sleep deprivation and stress, react differently than young adults. 124 young (18–30 years) and 94 older (60–72 years) healthy adults participated in one of four conditions: i. normal night sleep & Placebo-Trier Social Stress Test (TSST), ii. normal night sleep & Trier Social Stress Test, iii. sleep deprivation & Placebo-TSST, iv. sleep deprivation & TSST. Subjective stress ratings, heart rate variability (HRV), salivary alpha amylase (sAA) and cortisol were measured throughout the protocol. At the baseline pre-stress measurement, salivary cortisol and subjective stress values were higher in sleep deprived than in rested participants. However, the reactivity to and recovery from the TSST was not significantly different after sleep deprivation for any of the outcome measures. Older adults showed higher subjective stress, higher sAA and lower HRV at baseline, indicating increased basal autonomic activity. Cortisol trajectories and HRV slightly differed in older adults compared with younger adults (regardless of the TSST). Moreover, age did not moderate the effect of sleep deprivation. Taken together, the results show increased stress levels after sleep deprivation, but do not confirm the assumption that one night of sleep deprivation increases the responsivity to an acute psychosocial challenge.

  • 2017. Johanna Schwarz (et al.). Sleep Medicine 40 (Suppl. 1)

    Introduction: Mind wandering, the drift of attention from the current task at hand to self-generated thought is commonly associated with poorer performance, and could be a potential pathway through which sleep deprivation affects performance. Little is known about this, however. Therefore, the aim of the present study was to address the effect of sleep deprivation on mind wandering and performance in a sustained attention task. In addition, we studied age as moderating factor, since older individuals are generally less prone to mind wandering.

    Materials and methods: Healthy young (18-30years) and older (60-72years) subjects participated in either a normal night sleep (NSD) or a total sleep deprivation (SD) condition, i.e. 4 conditions: NSD (n=31), SD (n=30), NSDold (n = 24), SDold (n= 24). Performance was measured using the Sustained Attention to Response Task, during which 10 thought probes were included that prompted the subjects to answer a question on what they were you just thinking about, using predefined answer alternatives. Mind wandering was quantified as occurrence of task-unrelated thoughts.

    Results: Applying a 2 (age) X 2 (sleep deprivation) ANOVA, significant main effects for sleep deprivation and age were observed for omissions, indicating worse performance after sleep deprivation and in young participants (p's < .05). These main effects were dominated by an age*sleep deprivation interaction (p = .04), which was due to sleep deprivation causing significantly more omission errors in young subjects (Mean ±SEM; NSD: 2.3 ±0.9; SD: 13.1 ±4.1) but not in older subjects (NSDold: 1.9 ±0.4; SDold: 2.8 ±0.9).

    Likewise, main and interaction effects for age and sleep deprivation were significant for task-unrelated thoughts (p's < 0.01). Task unrelated thoughts were significantly more frequent after sleep loss in young (NSD: 1.5 ±0.2; SD: 4.3 ±0.6), but not older subjects (NSDold: 0.3 ±0.2; SDold: 0.5 ±0.2) (interaction age*sleep deprivation p < .01). Young subjects had significantly more task-unrelated thoughts than older, regardless of sleep condition.

    Task-unrelated thoughts correlated with errors of omission (r = 0.65, p < .001). Also, including task unrelated thoughts as covariate in the age * sleep deprivation ANOVA, main and interactions effect of age and sleep deprivation were no longer significant.

    Reaction time was significantly slower in older adults, but no main or interaction effect of sleep deprivation occurred. Errors of commission were not affected by condition.

    Conclusions: The results show that sleep deprivation caused both mind wandering and poorer task performance in young but not older participants. In addition, mind wandering rates correlated with errors of omission, which may indicate that a diminished ability to shut down off-task thoughts after sleep deprivation could be an important pathway to performance decrements after sleep loss. In line with previous research, mind wandering appears to occur less frequently in older individuals compared with younger. This lower occurrence of mind wandering in older subjects may potentially enable them to better maintain performance after sleep deprivation and partially explain the higher resilience of older adults to sleep deprivation.

  • 2017. Andreas Gerhardsson (et al.). Sleep Medicine 40 (Suppl. 1), e110-e110

    Introduction: Even though the occurrence of sleep problems increases with age, few studies have focused on the cognitive effects of acute sleep deprivation in elderly. Most previous research indicate that, compared to young, older adults show less impairment in e.g. attention after sleep deprivation. However, little is known of whether the same pattern holds for higher cognitive functions. In addition, while old age is usually related to a general decrease in working memory abilities, performance on working memory tasks may differ depending on the emotional valence of the stimuli, where positive stimuli seem to be beneficial for working memory performance in older adults. The aim of the present study was to investigate the effect of sleep deprivation on emotional working memory in older adults using two levels of working memory load.

    Materials and methods: A healthy sample of 48 old adults (MAge=66.69 years, SDAge=3.44 years) was randomized into a total sleep deprivation group (TSD; n=24) or a sleep control group (SC; n=24). They performed a working memory task (n-back) containing positive, negative and neutral pictures in a low (1-back) and a high (3-back) working memory load condition. Performance was measured as Accuracy (d'), Omissions and Reaction Time (RT).

    Results: For the d' and Omissions we performed two separate 2x2x3 (sleep, working memory load, valence) repeated measures analyses of variance (rmANOVA). For the RTs, we applied a mixed-effects model. For both d' and RT we found no effect of sleep deprivation (Ps > .05). For valence, we found main effects on both d' (F1,46 = 5.56, P=.005) and RT (F1,95.7 = 4.84, P=.01). d' did not differ for positive and neutral pictures, but was in both cases significantly better than for negative pictures. RTs were significantly faster for positive pictures. However, a working memory loadvalence interaction (F1,95.7 = 4.50, P=.01) further revealed an effect of valence in the low, but not in the high load condition. In the low load condition, RTs were faster for positive than for neutral pictures and faster for neutral than for negative pictures. There was no significant effect of Omissions.

    Conclusions: Our results showed that emotional working memory performance was not significantly affected by one night of sleep deprivation in older adults, which contrast what we found in a sample of young adults from the same project. In line with previous research, our results indicate a beneficial effect of positive stimuli on working memory in older adults. This effect was present in both groups and most pronounced for reaction times in the condition with a lower cognitive demand. We can conclude that, among older adults, the working memory performance is not impaired by sleep deprivation and that the benefits of positive stimuli on working memory seem intact. These findings contribute to a better understanding of older adults' cognitive functioning after sleep deprivation.

  • 2016. Andreas Gerhardsson (et al.). Abstracts of the 23rd Congress of the European Sleep Research Society, 13–16 September 2016, Bologna, Italy. Journal of Sleep Research, 25(S1), 17-18., 17-18

    Objectives: Emotional stimuli differently affect working memory (WM) performance. As sleep deprivation has a known impact on both emotion and WM our aim was to investigate how one night without sleep affects emotional WM performance. Methods: Healthy subjects (n = 56; age 18–30 years) were randomized to a total sleep deprivation (TSD) or a rested control (RC) condition. Subjects rated their affective state and performed a 1 and a 3-back WM task consisting of neutral, positive and negative pictures at 3 pm or 6 pm (balanced) the day after sleep manipulation. Accuracy (d’) and target response time (RT) were used as outcomes. Results: In the TSD condition, subjects rated themselves as less positive (P = 0.006) but not more negative than in the RC condition. In the WM task, TSD had a detrimental effect on accuracy (P = 0.03) regardless of difficulty. Moreover, accuracy was higher in the 1-back than in the 3-back (P < 0.001) and higher for neutral compared to both negative and positive stimuli (Ps < 0.05). RT was faster for positive compared to negative and neutral stimuli (Ps < 0.05). The latter effect was particularly pronounced in the TSD condition as shown by a condition*valence interaction (P < 0.03). Conclusions: One night of total sleep loss impaired emotional WM accuracy. Noticeable, RT was faster for positive stimuli compared to negative and neutral stimuli. This effect was particularly pronounced after sleep loss. This suggests that sleep loss strengthens the opposing effects of positive and negative stimuli on WM performance, possibly due to increased emotion reactivity.

  • 2016. Johanna Schwarz (et al.). Abstracts of the 23rd Congress of the European Sleep Research Society, 13–16 September 2016, Bologna, Italy. Journal of Sleep Research, 48-48

    Both sleep loss and social stress are risk factors for health and performance ability. It is assumed that sleep and stress are bidirectional linked, but most of the previous research has focused on studying sleep problems as consequence of stress. We believe that it is important to improve our understanding of the reverse connection, which is less studied. This presentation will cover recent experimental human studies that have investigated how sleep loss affects stress responses and whether it makes individuals more vulnerable to psychosocial stress. A study by Minkel et al. (Health Psychology, 2014) reported that the cortisol response to an acute stress situation was increased after sleep deprivation compared with a control condition indicating a more pronounced activation of the hypothalamic-pituitary-adrenal stress axis. I will also present recently collected data from young (18–30 years) and older (60–72 years) subjects that participated in four conditions (between subject design):

    (i) normal night sleep.

    (ii) normal night sleep & acute stress (Trier Social Stress Test).

    (iii) total sleep deprivation.

    (iv) total sleep deprivation & acute stress.

    The presentation thus provides state of the art knowledge of the link between sleep loss and vulnerability to stress.

  • 2015. Andreas Gerhardsson, Lennart Högman, Håkan Fischer. Frontiers in Psychology 6

    In our daily perception of facial expressions, we depend on an ability to generalize across the varied distances at which they may appear. This is important to how we interpret the quality and the intensity of the expression. Previous research has not investigated whether this so called perceptual constancy also applies to the experienced intensity of facial expressions. Using a psychophysical measure (Borg CR100 scale) the present study aimed to further investigate perceptual constancy of happy and angry facial expressions at varied sizes, which is a proxy for varying viewing distances. Seventy-one (42 females) participants rated the intensity and valence of facial expressions varying in distance and intensity. The results demonstrated that the perceived intensity (PI) of the emotional facial expression was dependent on the distance of the face and the person perceiving it. An interaction effect was noted, indicating that close-up faces are perceived as more intense than faces at a distance and that this effect is stronger the more intense the facial expression truly is. The present study raises considerations regarding constancy of the PI of happy and angry facial expressions at varied distances.

Visa alla publikationer av Andreas Gerhardsson vid Stockholms universitet

Senast uppdaterad: 15 november 2018

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