Mindfulness-based Cognitive Therapy For Depression Comorbid With Sleep Disturbances:the Effects And Potential Mechanism

Sleep disturbances(especially insomnia)and depression have complicated interplay.In recent years,a theoretical hypothesis of the causal sequence about the relationship between sleep and depression was proposed,in which sleep problem was triggered by some predisposing factors and persisted to alter the biological substrates and emotional responses to the internal and external stimuli.Gradully the cognitive system would be affected by the interaction between biological arousal and emotional reactivity,and then depression occurs.Although a great number of related researches have been achieved,some problems remain to be further explored.First of all,specific indicators of sleep problems which can predict depression are still unclear.In our study 1,the cross-section studies were used to explore the characteristics and sleep patterns of individuals with depression comorbid with sleep disturbances,to find the most closely related indicators of sleep which can predict the occurence and development of depression.Furthermore,to explore potential risk factors and possible protective factors that influences the relationship between sleep and depression.Secondly,based on the proposal of causal sequence between sleep problems and depression,we need to clarify the following questions:How do the sleep disturbances,depression symptoms reciprocally influence the effects of psychological intervention?What are their trajectories during the intervention?How to effectively treat with these symptoms?What are the short-term or long-term effects of the MBCT intervention?Therefore in study 2,23 eligible participants were recruited and received 8-weeks structured MBCT group training.Thirdly,the underlying mechanism of MBCT on depression comorbid with sleep disturbances may be related with cognitive conflict.Study 3 examined the conflict effect,conflict adaptation effect and interference effect in the emotional Flanker paradigm between comorbidty group and healthy control group,and also analysed and compared the above effects in comorbidty group before and after training.Results:1.68.4%out-patients which complained with sleep problems co-occurs different depressive symptoms.For non-clincial individuals,13.01%people suffered from comorbidity of depression and sleep disturbances.For PSQI and 7 sub-factors,comorbid group scored highest,healthy group the lowest.The score of perceived consequences of insomnia,worry about insomnia dimensions of DBAS-16 is the highest in comorbid group(P<0.001).Compared with the other three groups,the comorbid group reported highest scores in ATQ,reflecting rumination and total score of SRRS(P<0.001),while the total score of CFI was the lowest(P<0.001).For trait anxiety,PSS,comorbid group still got the highest level of the score(P<0.001).For CD-RISC,there were no obvious differences between comorbid group and pure depression group(P=0.982),but significant differences exist among other groups(P<0.001).For cognitive reappraisal,there were significant differences among comorbid group,pure sleep disturbances group and healthy group(P<0.05).The score of act with awareness,nonjudging,describing subfactors of FFMQ is the lowest in comorbid group(P<0.01).Pearson correlation analysis demonstrated that there were significantly positive correlations among PSQI,PSQI-sleep disturbances subfactor,SRRS,ATQ,trait anxiety and BDI(r=0.463~0.604,P<0.001),and negative correlation among DBAS,FFMQ,CD-RISC and BDI(r=-0.260~-0.335,P<0.001).Based on the results of regression analysis,we proposed potential risk models and protective models for the association between PSQI-daily disturbances and BDI.The structural equation modeling showed that DBAS,SRRS,ATQ played important mediating effects on the relationship between PSQI-daily disturbances and BDI.In addition,we further found mindfulness,cognitive flexibility as well as DBAS,SRRS,ATQ had chain mediating effects on the association between sleep and depression.Our study also found that high trait anxiety moderate the relationship between PSQI-daily disturbances and BDI.2.After 8-weeks MBCT group intervention,23 participants had significant improvements in depressive symptoms and sleep quality.The total score of BDI was reduced from pre-treatment 26.04 to post-treatment 12.91(cohen?s d=13.13,P<0.01),PSQI from 11.17(pre-treatment)to 7.61(post-treatment)(cohen?s d=3.57,P<0.01).Especially,sleep quality,sleep duration and daily dysfunction of PSQI improved significantly(P<0.01).The score of ISI also reduced from 12.74 to 9.26(cohen?s d=3.48,t=3.09,P<0.01).In post-training,the participants reported less dysfunctional beliefs and attitudes about sleep,such as worry about insomnia,sleep expectations and SRRS,ATQ(P<0.01).On the contrary,CFI,trait anxiety and MAAS for all participants increased after treatment(P<0.01).ANOVA for repeated measurement demonstrated that for PSQI and PSQI-daily disturbances,the interaction effect between time×the response level for treatment was significant(F(1,19)=13.93,P=0.001,?_P~2=0.423;F(1,19)=6.92,P=0.016,?_P~2=0.267respectively).Treatment responders reported less PSQI and PSQI-daily disturbances than non-responders after training.For DBAS,worry about insomnia,SRRS,trait anxiety,the interaction effect also significant(F(1,19)=7.84,P=0.011,?_P~2=0.292;F(1,19)=11.93,P=0.003,?_P~2=0.386;F(1,19)=7.91,P=0.011,?_P~2=0.294;(F(1,19)=6.45,P=0.02,?_P~2=0.254;F(1,19)=6.87,P=0.017,?_P~2=0.266 respectively).The score of DBAS,worry about insomnia was significantly increased which means treatment responders had fewer misconceptions about sleep,meanwhile that of the other factors(e.g.,SRRS,trait anxiety)were reduced for treatment responders at post-treatment(F=31.64,38.08,P<0.001).Based on results of the regression analysis,we found the change value of reflecting rummination,worry about insomnia totally mediated the relationships between that of PSQI-daily disturbances and BDI(c?=0.16,P=0.284).3.8-weeks Sleep&emotion diary were used to dynamically monitor the trajectory of sleep and emotion during the MBCT treatment.The results showed that sleep and emotion alternately changed.There was congruent trajectory between depression and wake time after sleep onset(WASO),and the same as anxiety and sleep latency.The change trend of daily fatigue also was consistent with that of anxiety.In addition,the least improvement was found in PSQI-daily disturbances.4.For 1-month follow up,the participants self-reported less BDI(11.32±10.13).Compared with the post-training(13.18±11.18),there was not significant differences(t=1.03,P>0.05).63.64%participants reported none or mild depressive symptoms.The decrease of ISI and brooding rumination at 1-month follow up was statistically significant(P<0.05).Cross-lagged analysis indicated that PSQI-daily disturbances and BDI were not reciprocally related to each other at 1-month timepoint.5.In emotional Flanker tasks,it was found that the error rates in comorbid group were obviously greater than healthy control group on the condition that the current trials were incongruent(P<0.05).MBCT treatment influenced the performance level of individual cognitive process in Flanker task.For all participants,the RTs of post-training in Flanker test were significantly shorter than that of pre-training(cohen?s d=98.42,P<0.01),especially for anger or happy faces(cohen?s d=71.13,106.71 respectively,P<0.01).However,the conflict adaptation effects and interference effects had no statistically significant(P>0.05).The changes in error rates for interference effect had significantly negative correlation with the changes of SRRS(r=-0.432,P=0.039).Conclusions:1.Poor sleep quality,nocturnal sleep disturbances,daytime dysfunction(less enthusiasm,fatigue)would be distinct sleep patterns and characteristics for individuals with depression comorbid with sleep disturbances.PSQI-daily disturbances directly predicted depression,and trait anxiety moderated the relationship between PSQI-daily disturbances and BDI.2.DBAS,SRRS,ATQ partially mediated the relationship between PSQI-daily disturbances and BDI,which aggravated the severity of depression.On the other hand,mindfulness,CFI would partially mediate the relationship between PSQI-daily disturbances and depression,and to alleviate the impact on depression through DBAS,SRRS,ATQ respectively.3.MBCT could better reduce the depressive symptoms,and some index of sleep(e.g.,sleep quality,sleep efficiency and sleep duration)on the condition of depression comorbid with sleep disturbances,but less improvement for daily disturbances of sleep.It was suggested that sleep daily disturbances could be the most important and intractable intervention target for individuals with depression comorbid with sleep problems.And the MBCT working mechanism on depression comorbid with sleep problems could be mediated by the changes of rumination,worry about insomnia and trait anxiety.Meanwhile the improvement of ATQ,MAAS,self-compassion would be common factors for the treatment effects,not some specific factors for depression comorbid with sleep disturbances.However,the reciprocally relationship to each other between PSQI-daily disturbances and BDI were not found at 1-month timepoint.It is necessary to increase the sample size and extend the observation period to complement the results in future study.4.Based on the comparison of behavioral data in Flanker emotional task before and after MBCT training for those individuals with depression comorbid with sleep problems,it was suggested that short-term MBCT training would improve more the ability of awareness of the current experience,not cognitive conflict of attention control.