| Background:Sleep is an essential part of people’s life and is vital for human’s physical and mental health.However,with the rapid development of mobile Internet technology,smart phones are becoming more and more popular.Using mobile phone during bedtime has also become a habit of many young adults.But it might have an impact on an individual’s sleep.Objectives:(1)To explore the relationship between bedtime mobile phone use and sleep,and to investigate the role of pre-sleep hyperarousal in the relationship between bedtime mobile phone use and sleep.(2)To evaluate whether 4 weeks with restricted use of mobile phone 30 minutes before sleep affect pre-sleep hyperarousal,sleep,mood,attention and working memory.Methods:Our study included two parts.First,a cross-sectional survey was conducted in a large sample of military college students(n=553).Self-designed demographic questionnaire,PSQI,PSAS and an item about bedtime mobile phone use were used to measure.Pearson correlation analysis,Spearman correlation analysis,mediation effect analysis and Bootstrap test were used for analysis.In the second part,thirty-eight participants were randomized to either intervention group(n=19),where members were instructed to avoid using their mobile phone 30 minutes before bedtime,or control group(n=19),where the participants were given no such instructions.Sleep habit,sleep quality,pre-sleep arousal and mood were measured using the sleep diary,the Pittsburgh sleep quality index,the Pre-sleep Arousal Scale and the Positive and Negative Affect Schedule respectively.Working memory and attention were tested by using the 0-,1-,2-back task(n-back task)and ANT task respectively.Assessments were conducted at baseline and post-intervention.The unpaired t-test and repeated measurement ANOVA were used for the analysis.Results:1.Among the 553 military college students,81.6 %were always used their mobile phones before bedtime.Bedtime mobile phone use was positively correlated with the sleep latency(r=0.131,p<0.01)and the total score of PSQI(r=0.255,p<0.01),while the relationship with sleep duration was not significant(r=0.068,p=0.109).Pre-sleep hyperarousal partially mediates the association between bedtime mobile phone use and sleep quality,which accounted for 42.86% of the total effect.2.In the randomized controlled study,after 1 month of intervention,we found there were significant interactions between groups and time regarding sleep latency(F(1,36)=6.665,p=0.014),sleep duration(F(1,36)=5.909,p=0.02)and PSQI(F(1,36)=11.919,p=0.001).Analysis of the simple effect test results showed significant differences in the between-group post-test in sleep latency(p=0.049)and in PSQI(p<0.01).There were significant differences over time in the intervention group in sleep latency(p<0.01),sleep duration(p=0.035)and PSQI(p<0.01).3.After 1 month of intervention,we found there was a significant interaction between groups and time regarding somatic(F(1,36)=6.378,p=0.016)and cognitive arousal(F(1,36)=4.547,p=0.040).Analysis of the simple main effect test results showed significant differences in the between-groups post-test in somatic arousal(p=0.008)and cognitive arousal(p=0.001).And we also found a significant difference(p<0.01)in somatic arousal and a significant difference(p<0.01)in cognitive arousal over time in the intervention group.4.After 1 month of intervention,we found there was a significant interaction between groups and time for positive affect(F(1,36)=7.677,p=0.009).Analysis of the simple main effect test results showed a significant difference in the between-groups post-test(p=0.01),and a significant difference(p=0.001)over time in the intervention group.There was a significant effect on the group regarding the negative affect(F(1,36)=8.840,p=0.005).5.After 1 month of intervention,we found working memory in the intervention group improved.For 1-back reaction time(RT),there was a significant interaction effect(F(1,36)=4.892,p=0.033)between groups and with time.Analysis of the simple main effect test results showed a significant difference(p=0.004)over time in 1-back RT in the intervention group and a marginal significant difference in the between-groups post-test(p=0.081).And there were only significant main effects of time in 0-back RT(F(1,36)=6.079,p=0.019),1-back accuracy(F(1,36)=5.017,p=0.031),2-back accuracy(F(1,36)=7.174,p=0.011)and 2-back RT(F(1,36)=18.537,p<0.01).In addition,no significant main effects of time(F(1,36)=1.635,p=0.209)and group(F(1,36)=1.414,p=0.242),and interaction effect(group × time)(F(1,36)=0.093,p=0.762)was found in 0-back accuracy.6.After 1 month of intervention,we found attention in the intervention group improved.For ANT-RT,a interaction effect of time × group was significant(F(1,36)=4.285,p=0.046).Simple effect analysis showed a significant difference(p=0.016)over time in the intervention group.In ANT-ACC,no significant main effects of time(F(1,36)=0.238,p=0.629)and group(F(1,36)=0.422,p=0.520),and time × group interaction effect(F(1,36)=2.774,p=0.105)was found.In alertness,main effect of time was significant(F(1,36)=10.356,p=0.003),and main effect of group was marginal significant(F(1,36)=3.922,p=0.055).In orientation,no significant main effects of time(F(1,36)=0.155,p=0.696),group(F(1,36)=0.424,p=0.519)and time × group interaction effect(F(1,36)=1.806,p=0.187)was found.In executive control,only the main effect of time was significant(F(1,36)=13.338,p=0.001).Conclusions:Using mobile phones before bedtime is associated with sleep quality among military college students,and pre-sleep hyperarousal partially mediates the association between bedtime mobile phone use and sleep quality.Reducing bedtime mobile phone use can improve sleep,reduce pre-sleep arousal,improve positive emotions,reduce negative emotions,and improve some cognitive functions. |
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