Abstract
Sleep deprivation and disorders are linked to reduced DMN connectivity. Less is known about how naturalistic sleep patterns – specifically sleep irregularity - relate to the DMN, particularly among adolescents and young adults. Additionally, no studies have utilized graph theory analysis to clarify whether sleep-related decreases in connectivity reflect global or local DMN changes. Twenty-five healthy adolescents and young adults (age range = 12–22; mean = 18.08; SD = 2.64, 56% female) completed 7 days of actigraphy and resting-state fMRI. Sleep regularity was captured by the Sleep Regularity Index (SRI) and the relationship between the SRI and DMN was examined using graph theory analysis. Analogous analyses explored relationships between the SRI and additional resting-state networks. Greater sleep regularity related to decreased path length (increased network connectivity) in DMN regions, particularly the right and left lateral parietal lobule, and the Language Network, including the left inferior frontal gyrus and the left posterior superior frontal gyrus. Findings were robust to covariates including sex and age. Sleep and DMN function may be tightly linked during adolescence and young adulthood, and reduced DMN connectivity may reflect local changes within the network. Future studies should assess how this relationship impacts cognitive development and neuropsychiatric outcomes in this age group.
Highlights
Sleep is integral to brain functioning and cognition[1]
As the Sleep Regularity Index (SRI) is a relatively new measure, it is notable that the mean and distribution of the SRI in the current sample is similar to a prior study in young adults[22] and was not associated with sex or age in the current sample
Consistent with our hypothesis, we found that increased sleep regularity was associated with a more efficient network structure within the default mode network (DMN) over and above other potential networks
Summary
Sleep is integral to brain functioning and cognition[1]. In the last decade, there has been growing interest in the impact of sleep on the spontaneous neuronal activity of the brain as assessed by resting-state functional connectivity magnetic resonance imaging[2]. Reduced DMN connectivity has been observed among young and elderly adults who report high levels of daytime sleepiness[7] as well as individuals diagnosed with insomnia and obstructive sleep apnea (OSA) disorders[3,5,20] Taken together, these studies suggest a close association www.nature.com/scientificreports between sleep and DMN connectivity and highlight a potential neural mechanism by which poor sleep results in cognitive deficits. Irregularity in sleep patterns among adolescents has been shown to be related to altered brain development, such as reduced white matter integrity, over and above the impact of shortened sleep duration[29], as well as reduced activation of the medial prefrontal cortex and striatum in response to reward[30]. These studies suggest that sleep regularity may be vital to brain development and function during adolescence
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