Wüst, Larissa Nadine. The role of sleep restriction, light intensity, and chronotype for alertness, mental effort, and cognition. 2024, Doctoral Thesis, University of Basel, Faculty of Psychology.
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Abstract
Short sleep duration at night and prolonged exposure to artificial light throughout the day are part of today’s lifestyle for many people. Sleep duration as well as light conditions can influence alertness. According to a proposed model (Lasauskaite & Cajochen, 2018) based on Brehm’s motivation intensity theory (Brehm & Self, 1989), alertness would influence perceived task demand, which in turn determines mental effort. Effort is the mobilization of resources to carry out instrumental behavior and expected to manifest in the sympathetic beta-adrenergic impact on the heart, indexed through cardiac pre-ejection period (PEP), but also systolic blood pressure (SBP). In the PhD project presented in this thesis, I have summarized existing
literature on effects of one night of sleep restriction on alertness and cognition and investigated effects of sleep restriction and light intensity on mental effort during a cognitive challenge.
In a series of meta-analyses, I summarized 44 studies that investigated alertness or cognitive performance after one night of sleep restriction (chapter 4). Separate analyses were run for subjective sleepiness, sustained attention, choice reaction time tasks, cognitive throughput, working memory, and inhibitory control, and, if available, for reaction time and accuracy. Significant increases in subjective sleepiness were observed (p < .0001), that were not associated with sleep duration in the sleep restriction condition (p = .039, significance level .01). Additionally, reaction time (p < .0001) and the number of attentional lapses (p < .0001), i.e., failure to respond within 500 ms from stimulus onset, in sustained attention tasks increased after sleep restriction. No significant effects were found for other cognitive domains (ps > .073).
In two experimental studies, I investigated the influence of sleep duration and light intensity on mental effort (chapter 5). Therefore, 40 participants (24 women) were recruited for Study 1 and 24 participants (16 women) for Study 2. The experimental protocol for both studies included a sleep-duration manipulation (5 h vs. 8 h, within-subjects) during the night before an experimental session in the morning. In Study 1, experimental sessions consisted of an 8-min cardiovascular baseline, 15-min exposure to the experimental light condition (1 lux vs. 65 lux at eye level, between-subjects), and a 5-min auditory 2-back task. For Study 2, a 5-min Karolinska Drowsiness Test was added after the baseline period and each experimental session then had two blocks of 15-min light exposure (100 lux vs. 500 lux, within-subjects) and 5-min modified auditory Sternberg task each. Cardiovascular measurements were recorded throughout the entire experimental sessions. In Study 1, mental effort, reflected through cardiovascular reactivity, was not significantly influenced by sleep duration nor light intensity. Mental effort during the first minute of task performance was higher in the participants who reported lower alertness (p = .041), suggesting disengagement from task performance in participants reporting high alertness. Study 2 showed stronger effort after sleep restriction,
indicated through SBP and DBP reactivity (ps < .001). PEP response was stronger in the higher light intensity condition (p = .032). These studies, for the first time investigated mental effort during a cognitive challenge after experimentally manipulated sleep duration and in different light intensities.
Chronotypes indicate a preference for a certain time of day, going along with sleep timing and the circadian clock, which is indicated by the time of evening melatonin onset. Early types exert less effort in a morning cognitive challenge, which corresponds to their optimal time, compared to an afternoon challenge (Carbajal et al., 2019). In an additional explorative analysis on Study 1, I investigated effects of chronotypes, determined from self-reported sleep time and from timing of melatonin onset, on mental effort during a cognitive challenge in the morning (chapter 6). Applying a Bayesian statistical approach, results indicated inconclusive results for PEP (BF10 = 0.631) and task performance (BF10 = 0.814), and no differences in SBP (BF10 = 0.268) between sleep onset-derived chronotypes. Chronotypes derived from timing of melatonin onset did not differ in alertness, task performance, or mental effort (BFs10 < 0.263), when the timing of the cognitive challenge was adapted to habitual sleep times, thus minimizing differences in circadian timing.
Taken together, results of the empirical studies suggest that sleep restriction would increase mental effort, but excessive sleepiness might result in disengagement from task performance. Effects appeared smaller than expected, therefore future studies should employ larger samples to prevent a lack of statistical power.
literature on effects of one night of sleep restriction on alertness and cognition and investigated effects of sleep restriction and light intensity on mental effort during a cognitive challenge.
In a series of meta-analyses, I summarized 44 studies that investigated alertness or cognitive performance after one night of sleep restriction (chapter 4). Separate analyses were run for subjective sleepiness, sustained attention, choice reaction time tasks, cognitive throughput, working memory, and inhibitory control, and, if available, for reaction time and accuracy. Significant increases in subjective sleepiness were observed (p < .0001), that were not associated with sleep duration in the sleep restriction condition (p = .039, significance level .01). Additionally, reaction time (p < .0001) and the number of attentional lapses (p < .0001), i.e., failure to respond within 500 ms from stimulus onset, in sustained attention tasks increased after sleep restriction. No significant effects were found for other cognitive domains (ps > .073).
In two experimental studies, I investigated the influence of sleep duration and light intensity on mental effort (chapter 5). Therefore, 40 participants (24 women) were recruited for Study 1 and 24 participants (16 women) for Study 2. The experimental protocol for both studies included a sleep-duration manipulation (5 h vs. 8 h, within-subjects) during the night before an experimental session in the morning. In Study 1, experimental sessions consisted of an 8-min cardiovascular baseline, 15-min exposure to the experimental light condition (1 lux vs. 65 lux at eye level, between-subjects), and a 5-min auditory 2-back task. For Study 2, a 5-min Karolinska Drowsiness Test was added after the baseline period and each experimental session then had two blocks of 15-min light exposure (100 lux vs. 500 lux, within-subjects) and 5-min modified auditory Sternberg task each. Cardiovascular measurements were recorded throughout the entire experimental sessions. In Study 1, mental effort, reflected through cardiovascular reactivity, was not significantly influenced by sleep duration nor light intensity. Mental effort during the first minute of task performance was higher in the participants who reported lower alertness (p = .041), suggesting disengagement from task performance in participants reporting high alertness. Study 2 showed stronger effort after sleep restriction,
indicated through SBP and DBP reactivity (ps < .001). PEP response was stronger in the higher light intensity condition (p = .032). These studies, for the first time investigated mental effort during a cognitive challenge after experimentally manipulated sleep duration and in different light intensities.
Chronotypes indicate a preference for a certain time of day, going along with sleep timing and the circadian clock, which is indicated by the time of evening melatonin onset. Early types exert less effort in a morning cognitive challenge, which corresponds to their optimal time, compared to an afternoon challenge (Carbajal et al., 2019). In an additional explorative analysis on Study 1, I investigated effects of chronotypes, determined from self-reported sleep time and from timing of melatonin onset, on mental effort during a cognitive challenge in the morning (chapter 6). Applying a Bayesian statistical approach, results indicated inconclusive results for PEP (BF10 = 0.631) and task performance (BF10 = 0.814), and no differences in SBP (BF10 = 0.268) between sleep onset-derived chronotypes. Chronotypes derived from timing of melatonin onset did not differ in alertness, task performance, or mental effort (BFs10 < 0.263), when the timing of the cognitive challenge was adapted to habitual sleep times, thus minimizing differences in circadian timing.
Taken together, results of the empirical studies suggest that sleep restriction would increase mental effort, but excessive sleepiness might result in disengagement from task performance. Effects appeared smaller than expected, therefore future studies should employ larger samples to prevent a lack of statistical power.
Advisors: | Cajochen, Christian |
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Committee Members: | de Quervain, Dominique J.-F. and Wright, Rex and Lasauskaite, Ruta |
Faculties and Departments: | 03 Faculty of Medicine > Bereich Psychiatrie (Klinik) > Erwachsenenpsychiatrie UPK > Kognitive Neurowissenschaften (de Quervain) 03 Faculty of Medicine > Departement Klinische Forschung > Bereich Psychiatrie (Klinik) > Erwachsenenpsychiatrie UPK > Kognitive Neurowissenschaften (de Quervain) 07 Faculty of Psychology > Departement Psychologie > Ehemalige Einheiten Psychologie > Cognitive Neuroscience (de Quervain) |
UniBasel Contributors: | Cajochen, Christian and de Quervain, Dominique J.-F. and Lasauskaite, Ruta |
Item Type: | Thesis |
Thesis Subtype: | Doctoral Thesis |
Thesis no: | 15539 |
Thesis status: | Complete |
Number of Pages: | IX, 146 |
Language: | English |
Identification Number: |
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edoc DOI: | |
Last Modified: | 15 Nov 2024 05:30 |
Deposited On: | 14 Nov 2024 15:31 |
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