Abstract
BackgroundSleep plays an important role in vulnerability to mood disorders. However, despite the existence of sex differences in vulnerability to mood disorders, no study has yet investigated the sex effect on sleep network organization and its potential involvement in vulnerability to mood disorders. The aim of our study was to empirically investigate the sex effect on network organization during REM and slow-wave sleep using the effective connectivity measured by Granger causality.MethodsPolysomnographic data from 44 healthy individuals (28 men and 16 women) recruited prospectively were analysed. To obtain the 19 × 19 connectivity matrix of all possible pairwise combinations of electrodes by Granger causality method from our EEG data, we used the Toolbox MVGC multivariate Granger causality. The computation of the network measures was realized by importing these connectivity matrices into EEGNET Toolbox.ResultsIn men and women, all small-world coefficients obtained are compatible with a small-world network organization during REM and slow-wave sleep. However, compared to men, women present greater small-world coefficients during REM sleep as well as for all EEG bands during this sleep stage, which indicates the presence of a small-world network organization less marked during REM sleep as well as for all EEG bands during this sleep stage in women. In addition, in women, these small-world coefficients during REM sleep as well as for all EEG bands during this sleep stage are positively correlated with the presence of subclinical symptoms of depression.ConclusionsThus, the highlighting of these sex differences in network organization during REM sleep indicates the presence of differences in the global and local processing of information during sleep between women and men. In addition, this small-world network organization less marked during REM sleep appears to be a marker of vulnerability to mood disorders specific to women, which opens up new perspectives in understanding sex differences in the occurrence of mood disorders.
Highlights
At the cerebral level, there are several elements in favour of the presence of a small-world network (SWN) organization both during wakefulness and sleep [1,2,3,4]
In order to test these hypotheses, we investigated empirically the sex effect on SWN organization during rapid eye movement (REM) and slow-wave sleep as well as for all EEG bands during these sleep stages using the effective connectivity measured by the Granger causality in healthy individuals
Woman sex is positively correlated with small-world coefficient (SWC) only for REM sleep as well as for all EEG bands during this sleep stage. In women, these SWC during REM sleep as well as for all EEG bands during this sleep stage are positively correlated with the presence of subclinical symptoms of depression
Summary
There are several elements in favour of the presence of a small-world network (SWN) organization both during wakefulness and sleep [1,2,3,4]. In the literature, there are many arguments in favour of a cerebral sex dimorphism at the anatomical, morphological, metabolic, neurochemical and neurophysiologic level [12, 13] This cerebral sex dimorphism is characterized by the presence of specific patterns of SWN organization in men and women during wakefulness, which seems to indicate the existence of sex differences in the cerebral processing of information [14,15,16,17,18,19,20]. This potential effect of sex on SWN organization has not yet been investigated during sleep. The aim of our study was to empirically investigate the sex effect on network organization during REM and slow-wave sleep using the effective connectivity measured by Granger causality
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
