Stress dynamically reduces sleep depth: temporal proximity to the stressor is crucial

Abstract

The anticipation of a future stressor can increase worry and cognitive arousal and has a detrimental effect on sleep. Similarly, experiencing a stressful event directly before sleep increases physiological and cognitive arousal and impairs subsequent sleep. However, the effects of post- vs. pre-sleep stress on sleep and their temporal dynamics have never been directly compared. Here, we examined the effect of an anticipated psychosocial stressor on sleep and arousal in a 90-min daytime nap, in 33 healthy female participants compared to an anticipated within-subject relaxation task. We compared the results to an additional group (n = 34) performing the same tasks directly before sleep. Anticipating stress after sleep reduced slow-wave activity/beta power ratio, slow-wave sleep, sleep spindles, and slow-wave parameters, in particular during late sleep, without a concomitant increase in physiological arousal. In contrast, pre-sleep psychosocial stress deteriorated the same parameters during early sleep with a concomitant increase in physiological arousal. Our results show that presleep cognitions directly affect sleep in temporal proximity to the stressor. While physiological arousal mediates the effects of presleep stress on early sleep, we suggest that effects during late sleep originate from a repeated reactivation of mental concepts associated with the stressful event during sleep.

The moderating role of conscientiousness in the temporal association between stress and sleep

“…For instance, studies have demonstrated alterations in sleep architecture, such as sleep spindles and slow wave sleep, following induced stress during a nap. 5 To further disentangle the association between stress and sleep, objective markers of stress such as cortisol, heart rate variability, or blood pressure could be assessed.…”

“…[2][3][4] Even the anticipation of a future stressor, like an exam, can increase worry and cognitive arousal and has a detrimental effect on sleep. 5 These studies often averaged sleep variables over multiple days and used trait stress measures ignoring the dynamic interplay between stress and sleep.…”

“…Inducing acute stress right before taking a nap mainly impacted early sleep possibly due to enhanced physiological arousal. 5 While the anticipation of stressful events after sleep affected later sleep periods of the nap possibly due to prolonged cognitive arousal. Many factors might moderate this relationship between stress and sleep, such as personality traits.…”

Sleep spindles, stress and PTSD: The state of the science and future directions

“…Of note, however: this focused review did not cover the full extent of published literature on spindles and stress more generally. For example, a still sparse body of studies report associations between sleep spindles and stress-related insomnia ( Dang-Vu et al, 2015 ) and spindles as a potential indicator of stress-related sleep disturbance( Beck et al, 2022 ).…”

“…There is also a burgeoning literature demonstrating that features of sleep spindles vary in a state-like fashion, such as in the context of learning, and that they may be associated with certain psychiatric conditions ( Fernandez and Luthi 2020 ). In psychiatric disorders, they have been most extensively studied in schizophrenia ( D'Agostino et al, 2018 ), but there is now early research examining their characteristics and function in the context of stress and stress disorder research ( Dang-Vu et al, 2015 ; Beck et al, 2022 ; Denis et al, 2022 ), especially posttraumatic stress disorder (PTSD) ( Wang et al, 2020a ; Denis et al, 2021 ; van der Heijden et al, 2022 ).

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