0063 Preliminary Examination of the Effects of Long-Term Sleep Restriction on Intrinsic Brain Circuitry

Abstract

Introduction: Short sleep duration promotes metabolic dysregulation and obesity. We have previously shown that acute sleep restriction increases neuronal activity in response to food stimuli in areas of interoception and reward, such as the insula and orbitofrontal cortex. However, whether chronic mild sleep restriction impacts food reward valuation in the brain remains unknown. In an ongoing study, we assess the effects of mild 6‐week sleep restriction on intrinsic functional connectivity (iFC) across reward and interoception‐ related brain circuitry. Methods: To date, 16 adult men and women (age 29.0±5.3 years and BMI 26.9±2.6 kg/m2at study entry) took part in this randomized, crossover, outpatient trial of 2 phases: habitual sleep (HS; ≥7 h/night) and sleep restriction (SR; ‐1.5 h/night relative to HS). All participants were screened with actigraphy over a two‐week period to ensure adequate sleep duration of 7‐9 h/night (average screening total sleep time: 7.65±0.58 h/night). Two resting‐state (task‐free) functional MRI scans (Siemens Skyra 3T, TR=2.5s, two 5‐min runs) were collected during the final week of each phase. Here we report preliminary analyses using the Data Processing & Analysis of Brain Imaging V2.3‐170105 toolbox with paired‐sample t‐tests across the whole brain. Results: Average sleep duration in the HS phase was 7.55±0.55 h/ night vs. 6.10±0.49 h/night during SR (p<0.0001). Examining iFC of 17 previously studied regions‐of‐interest relevant to food valuation and interoception yielded two significant results after correction for Gaussian Random Field (p<0.001 at voxel level, cluster p<0.05). iFC was greater following SR than HS for (1) left inferior frontal gyrus with medial prefrontal cortex (mPFC); and (2) mPFC with bilateral superior temporal gyrus. Conclusion: This study provides preliminary evidence of decreased segregation between a key anterior node of the default mode network (mPFC) and nodes of the salience and somatosensory (auditory) networks under prolonged mild SR. Such iFC changes, suggesting atypical network coupling, if confirmed in the completed sample, will be examined in the future in relation to key measures of metabolism and cardiovascular risks.