Sleep microstructure: effects of nighttime noise exposure and age

Rudzik, Franziska Helen. Sleep microstructure: effects of nighttime noise exposure and age. 2019, Doctoral Thesis, University of Basel, Faculty of Psychology.


Official URL: http://edoc.unibas.ch/diss/DissB_13375

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Transient activation phases during sleep (i.e., cortical arousals, or autonomic arousals) are generally considered to fragment sleep and, as a result, negatively impact the recuperative value of sleep (Bonnet & Arand, 2003; Wesensten, Balkin, & Belenky, 1999). Transient activation phases can occur in response to external stimuli, such as transportation noise (Basner, Müller, & Elmenhorst, 2011); they also increase with aging without external stimuli and are part of the normal aging process in humans (Bonnet & Arand, 2007; Mander, Winer, & Walker, 2017). Sleep spindles–spontaneous non-rapid eye movement sleep-related brain oscillations that also decline with aging (Purcell et al., 2017)–modify external information processing and might serve as a physiological marker of sleep-related noise sensitivity (Dang-Vu, McKinney, Buxton, Solet, & Ellenbogen, 2010).
Twenty-six young (19-33 years, 12 women) and 16 older (52-70 years, 8 women) healthy volunteers underwent a repeated measures six-day laboratory study. Participants spent two noise-free nights (first and last night) and four transportation noise exposure nights (three nights with road and one with railway noise exposure in an incompletely counterbalanced sequence), two with continuous and two characterized by eventful noise (average sound levels of 45 dB, maximum sound levels between 50 and 62 dB for eventful noise). During the nights, polysomnography and body movements were recorded. Subjective sleep quality was assessed every morning and subjective sleepiness was assessed twenty times during scheduled wakefulness. Sleep staging and EEG arousal scoring followed standard criteria; sleep spindle characteristics and additional arousal response events (autonomic arousals and body movements) were identified by automatic detection algorithms.
In the older individuals, sleep was more fragmented under noise exposure compared to noise-free nights, while there were no effects on sleep macrostructure and all-night arousal and awakening rates in the young, which were independent of time-in-study effects. Arousal rate variation within NREM sleep cycles was best described by a u-shaped course with variations across cycles. Older participants had higher overall arousal rates than the younger individuals with differences for the first and the fourth cycle depending on the age group. During eventful noise exposure nights, overall arousal rates were increased compared to noise-free nights. Sleep spindle rates showed an age-related decline along with more noise-induced sleep alterations. Sleep structure and continuity were not differentially affected by noise exposure in individuals with a low versus a high spindle rate. For all investigated arousal response markers (cortical arousals, awakenings, autonomic arousals, and body movements), the probability of an event-related response during eventful road and railway noise exposure nights was significantly higher than spontaneous probabilities. Awakening and EEG arousal probability from single railway noise events depended on individual (e.g., age), acoustical (e.g., maximum sound pressure level and maximum slope of the sound pressure level), and situational factors (e.g., sleep stage, time of night), but was not affected by the all-night spindle rate.
Overall, the data suggest small effects of transportation noise exposure on sleep macro- and microstructure and a remarkable ability of the sleeping brain to adapt to nighttime noise. Sleep spindles are trait-like transitory EEG oscillations, which may reflect stable sleep but do not necessarily protect the sleeper against external stimuli such as nighttime transportation noise. Furthermore, when evaluating the effects of aging and nighttime noise exposure on sleep fragmentation, the physiological microstructural evolution needs to be considered.
Advisors:Greifeneder, Rainer and Cajochen, Christian
Faculties and Departments:07 Faculty of Psychology > Departement Psychologie > Society & Choice > Sozialpsychologie (Greifeneder)
UniBasel Contributors:Greifeneder, Rainer and Cajochen, Christian
Item Type:Thesis
Thesis Subtype:Doctoral Thesis
Thesis no:13375
Thesis status:Complete
Number of Pages:1 Online-Ressource (158 Seiten)
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Last Modified:01 Mar 2021 02:30
Deposited On:25 Nov 2019 14:56

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