Circadian Rhythm Disorders and Corresponding Functional Brain Abnormalities in Young Female Nurses: A Preliminary Study

Abstract

Objective: Shift work is associated with a decrease in melatonin level and perturbation of the circadian rhythm; however, it is unknown if these lead to functional brain changes. In this study, we investigated whether circadian rhythm disorders caused by shift work are related to changes in brain functional connectivity (FC) and regional homogeneity (ReHo) using whole-brain resting-state functional magnetic resonance imaging (fMRI).Methods: This prospective case-control study included nine female night shift nurses and nine age-matched female day work nurses with normal sleep rhythms. To assess sleep quality and mood, participants were asked to complete questionnaires. Serum melatonin and cortisol levels were measured. ReHo of whole-brain resting-state function and seed-based FC of the bilateral hypothalamus were compared between groups. Variables that differed significantly between groups were used to examine the association between questionnaire scores and hormone levels and fMRI data.Results: The night shift nurses had significantly lower sleep quality and melatonin levels; lower ReHo activation in the bilateral cerebellar hemisphere and higher ReHo in the bilateral occipital lobe and left parietal lobe; and higher FC from the hypothalamus to the right cingulate gyrus, right putamen, and vermis than did the day shift nurses. Activation of the right cerebellar hemisphere left superior parietal gyrus, and the right superior occipital gyrus was correlated with sleep quality scores. Moreover, activation of the right cerebellar hemisphere (r = 0.583, P = 0.011) was correlated with melatonin levels, and higher sleepiness scores were associated with stronger FC between the hypothalamus and vermis (r = 0.501, P = 0.034).Conclusions: Circadian rhythm disorder caused by night shift work can lead to a decrease in sleep quality and melatonin level, as well as a series of changes in brain FC and ReHo.

A multidisciplinary perspective on the complex interactions between sleep, circadian, and metabolic disruption in cancer patients

“…In addition to inflammatory cytokines, circulating levels of the circadian hormones melatonin and cortisol are central outputs of sleep but also regulators of the sleep–wake cycle themselves. Lower levels of melatonin were associated with lower sleep quality in healthy female nurses working night shifts compared with age-matched female nurses working the day shifts [ 56 ]. Furthermore, Mazzoccoli et al [ 57 ] found that elderly patients with advanced stage of lung cancer exhibited decreased melatonin levels and melatonin/cortisol ratios in the serum compared to healthy, age-matched controls.…”

Attention Performance Correlated With White Matter Structural Brain Networks in Shift Work Disorder

“…To date, numerous studies on functional abnormalities in SWD have been detected via functional magnetic resonance imaging (fMRI) (9,10). One study on night shift nurses has shown higher ReHo in the bilateral occipital lobe and left parietal lobe and lower regional homogeneity (ReHo) in the bilateral cerebellar hemisphere in contrast with the day shift nurses (10).…”

“…To date, numerous studies on functional abnormalities in SWD have been detected via functional magnetic resonance imaging (fMRI) (9,10). One study on night shift nurses has shown higher ReHo in the bilateral occipital lobe and left parietal lobe and lower regional homogeneity (ReHo) in the bilateral cerebellar hemisphere in contrast with the day shift nurses (10). Another study on SWD has revealed disrupted functional connectivity between default mode network and sensorimotor network, left frontoparietal network, and salience network (9).…”

Circadian Variation of Migraine Attack Onset Affects fMRI Brain Response to Fearful Faces

“…Specifically, areas of pain processing, including for example middle cingulate cortex (MCC), postcentral gyrus from Study 1 and precentral gyrus, supplementary motor area (SMA) from Study 2; and regions of sensory processing, including Heschl’s gyrus, precuneus from Study 1 and paracentral lobule from Study 2 were detected. These regions are thought to contribute to migraine attacks (for a review see Schwedt et al, 2015 ), and some of them also associated with circadian rhythm-related phenomena in previous fMRI studies, including precuneus ( Kyeong et al, 2017 ; Facer-Childs et al, 2019 ), postcentral gyrus ( Kyeong et al, 2017 ; Fafrowicz et al, 2019 ), precentral gyrus ( Kyeong et al, 2017 ), posterior cingulate cortex (PCC) ( Kyeong et al, 2017 ), and MCC ( Wu et al, 2021 ).…”