Profiles

Johanna Schwarz

Johanna Schwarz

Forskare

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Telephone 08-553 789 32
Email johanna.schwarz@su.se
Visiting address Frescati Hagväg 16 A
Room 337
Postal address Stressforskningsinstitutet 106 91 Stockholm

About me

Currently, Johanna works as a researcher at the Department of Biological Psychology and treatment research at the Stress Research Institute, where she previously has been an exchange doctoral student since 2007. Her main research area is the effects of sleep deprivation and sustained wakefulness on driving-related functions and real road driving performance, subjective and physiological sleepiness. Moreover, she is interested in how genes, in particular the PERIOD3 polymorphism, contribute to inter-individual differences in vulnerability to sleep deprivation. Another main project Johanna is currently involved in focuses on sleep in women. Women have a high prevalence of sleep complaints, but the results on objective sleep quality are inconclusive. The longitudinal study aims to investigate the development over time of sleep complaints in women and to relate the complaints to physiological sleep quality.

Education: Johanna is a psychologist and received her doctorate in 2012, at the Department of Psychology at the University of Regensburg, Germany.

Publications

A selection from Stockholm University publication database
  • Karin Schraml, Johanna Schwarz, Aleksander Perski.
  • 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.

  • 2018. Torbjörn Åkerstedt (et al.). Journal of Sleep Research 27 (4)

    Bedtime is frequently delayed by many factors in life, and a homeostatic response to the delay may compensate partly for increased time awake and shortened sleep. Because sleep becomes shorter with age and women complain of disturbed sleep more often than men, age and sex differences in the homeostatic response to a delayed bedtime may modify the homeostatic response. The purpose of the present study was to investigate the effect of late-night short-sleep (3 h with awakening at about 07:00 hours) on in-home recorded sleep in men and women in two age groups (20-30 and 65-75 years). Results (N = 59) showed that late-night short-sleep was associated with an increase in percentage of N3 sleep and a decrease in percentage of rapid eye movement sleep, as well as decreases in several measures of sleep discontinuity and rapid eye movement density. Men showed a smaller decrease in percentage of rapid eye movement sleep than women in response to late-night short-sleep, as did older individuals of both sexes compared with younger. Older men showed a weaker percentage of N3 sleep in response to late-night short-sleep than younger men. In general, men showed a greater percentage of rapid eye movement sleep and a lower percentage of N3 sleep than women, and older individuals showed a lower percentage of N3 sleep than younger. In particular, older men showed very low levels of percentage of N3 sleep. We conclude that older males show less of a homeostatic response to late-night short-sleep. This may be an indication of impaired capacity for recovery in older men. Future studies should investigate if this pattern can be linked to gender-associated differences in morbidity and mortality.

Show all publications by Johanna Schwarz at Stockholm University

Last updated: March 15, 2019

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