Study On The Vulnerability Of Subjective Alertness And Objective Vigilance To Sleep Deprivation

With the in-depth study of sleep deprivation by researchers,the effect of sleep deprivation on the brain cognition is no longer considered,or is not limited to "lost the benefits of sleep." In fact,the effects of sleep deprivation on the human brain are very extensive.Sleep deprivation could impair all cognitive domains,from vigilance,attention,perception to advanced cognitive functions.Sleep deprivation has become a widespread phenomenon in the current society.After insufficient sleep,most people will choose compensatory sleep to try to eliminate the adverse effects of insufficient sleep or sleep deprivation,but sleep deprivation still has a long-term irreversible effect on the brain.The problem of lack of sleep has a huge impact on many fields such as economy,health,education,etc.It is of far-reaching practical significance to conduct in-depth research in this field.Sleep deprivation vulnerability refers to the degree of susceptibility of an individual's psychological behavior characteristics to sleep deprivation.Individuals with high vulnerability to sleep deprivation suffer greater damage to their psychological behavior after experiencing sleep deprivation for the same length of time.Vulnerability of sleep deprivation is a characteristic attribute of large differences between subjects and stability within the subjects.But the same individual owns the high vulnerability to sleep deprivation on one behavioral characteristic does not mean that he/her would own the high vulnerability on another behavioral characteristic.That is "task-dependent".There is also an inherited factor in the cross-task vulnerability difference.Previous studies have found that,the level of individual objective vigilance vulnerability to sleep deprivation is not related to the level of subjective alertness vulnerability to sleep deprivation.It is reported that there are three independent factors behind vulnerability: The first is the subjective assessment of sleepiness,which includes all the subjectively reported indicators;The second is cognitive processing,which includes task measurement of cognitive processing speed and executive function;The last one is objective vigilance.But the brain mechanism behind these independent factors on sleep deprivation vulnerability is still unclear.In this study we focused on the neural mechanism behind the separation of subjective alertness and objective vigilance in terms of sleep deprivation vulnerability.Through 36 hours of sleep deprivation on 33 subjects,we collected the vigilance and alertness data obtained at 9 sampling time points.we found in Study 1 that although with the increase in the time length of sleep deprivation,the overall fluctuating trends of the objective vigilance(measured by Psychomotor Vigilance Test)and subjective alertness(measured by the Stanford Sleepiness Scale,Karolinska Sleepiness Scale and the Amsterdam Resting State Questionnaire)are very similar,there is no significant correlation between changes in subjective sleepiness and objective vigilance.In the second study,we hope to use resting state images acquired by functional MRI,combined with multivariate analysis method and the whole brain functional connectivity matrix,to investigate the neural mechanism behinds this phenomenon we found in Study 1.Participants who participated in Study 1 underwent resting state scans at three time points(sleep deprivation 0 hours,24 hours,36 hours)during the sleep deprivation experiment.First of all,we preprocessed the collected resting state data.After quality control and denoising,we performed a whole brain functional connectivity analysis on the image data,which was divided into 264 regions of interest and 13 brain networks.After variance analysis,we extracted the effective eigenvalues.Then we use multivariate statistical learning method(support vector machine)to predict the impaired objective vigilance and subjective sleepiness after sleep deprivation by the functional connectivity matrix.The leave-one-out cross-validation supports the good prediction performance of the model.Finally,through the permutation test combined with the bootstrapping test,we determined which connectivity have the significant contribution to the changes of subjective sleepiness and objective vigilance after sleep deprivation in the model prediction process.The analysis found that,compared with subjective sleepiness,there is a wider range of functional brain connectivities involved in the change of objective vigilance after sleep deprivation,including but not limited to connectivity between the subcortical network and the cortical network,connectivity within the subcortical network,connectivity within the somatosensory network,and connectivity between the ventral attention network and the frontal parietal control network.The subjective sleepiness change involves only a functional connectivity between the subcortical network and the sensorimotor network.Study 2 shows that the involvement of different brain functional connectivities is the reason why objective vigilance and subjective alertness are independent and on sleep deprivation vulnerability.On the one hand,this study used information from multiple time stages to reveal the difference of vulnerability of subjective alertness and objective vigilance to sleep deprivation and its neural mechanism.On the other hand,a neural network model is constructed that uses resting-state network function connectivities to predict subjective alertness and objective vigilance.This study can help to conduct more reasonable work management and organization for night shift staff.