UNIVERSITY GRADUATE SCHOOL BULLETIN ANNOUNCEMENT 

Florida International University 

University Graduate School 

Doctoral Dissertation Defense

Abstract

Structural and Functional Brain Alterations Linked with Sleep Disruption: Implications for Adolescent Substance Use 

by 

Katharine E. Crooks 

Sleep disruption is pervasive across development and clinical populations and is linked to cognitive impairment, behavioral dysregulation, and increased risk-taking. However, the multilevel neurobiological and behavioral mechanisms underlying these associations remain incompletely understood. This dissertation integrates three complementary studies to clarify how sleep disruption alters brain structure and function and how these neurobiological alterations relate to real-world behavioral and health-related outcomes including accidents, mishaps, and substance use (SU). 

In the first two studies, coordinate-based meta-analyses synthesized functional and structural neuroimaging findings from studies considering acute sleep disruption and chronic sleep disorders, respectively. Multiple meta-analytic strategies including activation likelihood estimation, meta-analytic connectivity modeling, and functional decoding were used to identify convergent brain alterations and their potential behavioral consequences. In the third study, I combined resting-state fMRI assessments with longitudinal behavioral data from adolescents to examine a mechanistic pathway linking sleep problems to future SU (i.e., e-cigarettes, cannabis, alcohol) via real-world cognitive failures and externalizing symptomatology. 

Meta-analytic outcomes  identified robust sleep disruption-related functional brain alterations in the dorsomedial prefrontal cortex (PFC), with sleep disorder-specific involvement of the ventrolateral PFC. Structurally, meta-analytic outcomes identified sleep disorder–related alterations in the thalamus, particularly the pulvinar, with parasomnia-specific involvement of the posterior cingulate cortex (PCC). Network-level analyses indicated that thalamic alterations were embedded in cortico-striato-thalamic circuits supporting attention and performance monitoring, whereas PCC alterations were embedded in valuation and reward-processing networks. Among adolescents, greater sleep problems were associated with altered thalamocortical connectivity, particularly with occipital and fusiform regions, and with higher levels of everyday cognitive failures and externalizing symptoms. Serial mediation models revealed that sleep problems indirectly predicted later e-cigarette and cannabis use (but not alcohol) through sequential increases in cognitive failures and externalizing behavior. 

Collectively, these findings indicate that sleep disruption compromises thalamocortical and valuation-related brain networks, increasing susceptibility to cognitive lapses and behavioral dysregulation that elevate SU risk. This work positions sleep as an upstream, modifiable neurocognitive risk factor for SU and highlights improving sleep as a promising prevention and early intervention target aimed at reducing cognitive impairment and maladaptive behavioral trajectories among adolescents. 

Date: March 26th, 2026            Department: Psychology 

Time: 2.00 p.m. Eastern           Major Professor: Dr. Matthew T. Sutherland 

Place: AHC4 Room 302