Functional connectivity of cortical resting-state networks is differentially affected by rest conditions.

Optimal conditions for resting-state functional magnetic resonance imaging (rs-fMRI) are still highly debated. Here, we comprehensively assessed the effects of various rest conditions on all cortical resting-state networks (RSNs) defined by an established atlas. Twenty-two healthy college students (22 ± 4 years old, 12 females) were scanned on a GE 3T MRI scanner. Rs-fMRI datasets were collected under four different conditions for each subject: (1) eyes open in dim light (Eyes-Open), (2) eyes closed and awake (Eyes-Closed), (3) eyes closed while remembering four numbers through the scan session (Eyes-Closed-Number) and (4) asked to watch a movie (Movie). We completed a thorough examination of the 17 functional RSNs defined by Yeo and colleagues. Importantly, the movie led to changes in global connectivity and should be avoided as a rest condition. Conversely, there were no significant connectivity differences between conditions within the frontoparietal control and limbic networks and the following subnetworks as defined by Yeo et al.: default-B, dorsal-attention-B and salience/ventral-attention-B. These were not even significant when compared to the highly stimulative Movie condition. A significant difference was not found between Eyes-Closed and Eyes-Closed-Number conditions in whole-brain, within-network and between-network comparisons. When considering other rest conditions, however, we observed connectivity changes in some subnetworks, including those of the default-mode network. Overall, we found conditions with more external stimulation led to more changes in functional connectivity during rs-fMRI. In conclusion, the comprehensive results of our study can aid in choosing rest conditions for the study of overall and specific functional networks.

Exercise during early pregnancy is associated with greater sleep continuity.

OBJECTIVES/BACKGROUND: Pregnant women report disturbed sleep beginning in early pregnancy. Among nonpregnant populations, exercise has been associated with improved sleep; however, research in pregnant samples has been equivocal. We examined whether varying degrees of exercise were associated with better nocturnal sleep among pregnant women during early gestation. PARTICIPANTS: 172 pregnant women. METHODS: Self-reported sleep and exercise and objective sleep were collected during early gestation: T1 (10-12 weeks), T2 (14-16 weeks), and T3 (18-20 weeks) from 172 pregnant women. Exercise was categorized into three time-varying groups: 0 metabolic equivalent minutes per week (MET-min/week), 1 to < 500 MET-min/week, or ≥ 500 MET-min/week. Linear mixed-effects models were employed to test hypotheses. RESULTS: A significant main effect for Time (F[2,254] = 9.77, p < 0.0001) and Time*Exercise group interaction were observed for actigraphic sleep efficiency (aSE) (F[4,569] = 2.73, p = 0.0285). At T2, women who reported ≥ 500 MET-min/week had higher aSE than those who reported 0 MET-min/week. Significant main effects for Exercise Group and Time were observed for actigraphic wake after sleep onset (aWASO; F[2,694] = 3.04, p = 0.0483 and F[2,260] = 3.21, p = 0.0419). aWASO was lowest for those reporting 1 to < 500 MET-min/week (t[701] = 2.35, adjusted p = .0489) and aWASO decreased from T1 to T3 (t[258] = 2.53, adjusted p value = 0.036). Lastly, there was a main effect for Time for the PSQI (F[2,689] = 52.11, p < 0.0001), indicating that sleep quality improved over time. CONCLUSIONS: Some level of exercise among pregnant women appears to be more advantageous than no exercise at all. Moderate exercise, while still unclearly defined, may be a worthwhile adjunct treatment to combat sleep disturbances during pregnancy.

Insomnia symptoms with objective short sleep duration are associated with systemic inflammation in adolescents.

Inflammation has been suggested as a potential pathway by which insomnia and short sleep can affect risk of morbidity in adults. However, few studies have examined the association of insomnia with inflammation in adolescents, despite accumulating evidence that pathophysiologic changes may already occur during this critical developmental period. The present study sought to examine the association of insomnia symptoms with systemic inflammation and the role of objective sleep duration in this association. Participants were 378 adolescents (16.9±2.3y, 45.8% female) from the Penn State Child Cohort, a population-based sample who underwent 9-h polysomnography (PSG) followed by a single fasting blood draw to assess plasma levels of C-reactive protein (CRP) and other inflammatory markers. Insomnia symptoms were defined by a self-report of difficulties falling and/or staying asleep, while objective sleep duration groups were defined as a PSG total sleep time ⩾8, 8-7, and ⩽7h. We assessed the association of insomnia symptoms, objective sleep duration, and their interaction with inflammatory markers, while adjusting for multiple potential confounders. Adolescents reporting insomnia symptoms had significantly higher levels of CRP compared to controls and a significant interaction (p<0.01) showed that objective sleep duration modified this association. Elevated CRP was present in adolescents with insomnia symptoms and ⩽7h of sleep (1.79mg/L) as compared to controls or adolescents with insomnia symptoms and ⩾8h of sleep (0.90mg/L and 0.98mg/L, respectively) or controls with ⩽7h of sleep (0.74mg/L; all p-values <0.01). In sum, insomnia symptoms with objective short sleep duration are associated with systemic inflammation as early as adolescence. This study suggests that chronic low-grade inflammation may be a common final pathway towards morbidity in adulthood in this insomnia phenotype.