Explore The Feature And Occurrence Condition Of Sleep-Related Attentional Bias In Insomnia

As a frequent healthy complaint,Insomnia is one of the most common sleep disorder,which is characterized by difficulties with intiating and/or maintaining sleep,or non-restorative sleep,as well as notable daytime impairment.Prominent models of insomnia(Harvey,2002;Espie,2006)posit that Sleep-related Attentional Bias plays an important role in the development and maintenance of insomnia.However,there still exists inconsistency between the findings of sleep-related attenional bias cross 20-year research,especially on illuminating the question about the influence factors.Thus,the present study conduct three experiments with the aim to futher explore the relation of insomnia and sleep-related attentional bias.Firstly,the aim of first experiment is to test the possible specificity of sleep-related attentional bias in insomnia,thus the valence of word stimuli were controlled.On total,25 insomnia subjects(INS:20 females,mean age 21.28±1.02 years)and 22 good sleep subjects(GS:19 females,mean age 21.18±1.05 years)were employed.A 2(group:INS/GS)×4(stimuli types:Threatening word pairs/sleep-negative word pairs/sleep-positive word paris/neutral word pairs)×3(SOL:200/500/1500 ms)mixed design was used.However,repeated-measures analysis of variance did not show any significant difference between INS and GS on attentional bias score of non-specified word,of sleep-negative word and of sleep-positive word.In other words,oppositing to the hypothesis,the valence did not affect the attentional bias significantly.The analysis obtained the similar insignificant result when add variance of time(SOL)into repeat-measures.Since some suggests that visual dot probe task was not optimal paradigm when using words as materials,and reaction time measures have some shortcomings(e.g."snapshot" nature and the distal relation between key press and attention),first experiment may lack sufficient power to dectect the effect.To overcome those obstacles,Eye Tracking Technology was added into second experiment with a replacement of words by pictures.The experiment was taken the 2(group:INS/GS)x4(stimuli types:Threatening picture pairs/sleep-negative picture pairs/sleep-positive picture paris/neutral picture pairs)mixed design.The subjectcs recruited in second experiment were the same groups employed in first experiment.Although the pattern of RT datas shows significant interactions in the index of maintenance(INS is more likely to avoid sleep-positive picture compared to GS)and overall attentional bias score(GS is less likely to foucus on non-specificed threatening pictures),the analysis of eye movement datas did not support this effect with non-significant result.Given the null findings of first two experiments,the last experiments was intended to test a possibility that the failure to detect the effect of sleep-related attentional bias is due to neglect of considering pre-sleep quality(or the current state of insomnia)of subjects.It is reasonable to deduce that sleep-related attentional bias may be related to poor sleep quality,for recent studies consistently found that insomniacs appeared to cycle between good and bad sleep rather than being sleepless everyday.Therefore,a 2(group:INS/GS)x4(stimuli types:Threatening picture pairs/sleep-negative picture pairs/sleep-positive picture paris/neutral picture pairs)×2(manipulation:bad night/reading recall)mixed design was used to preliminarily study the occurrence condition of sleep-related attentional bias.On total,31 insomnia subjects(INS:23 females,mean age 19.55 ± 0.89 years)and 34 good sleep subjects(GS:24 females,mean agel9.50±0.86 years)were employed in third experiment.As we expected,the results of third experiment indicated that only after inducing by a bad night recall(not by reading recall),INS(compared to GS)displayed much stronger attentional bias toward both sleep-related stimuli and negative stimuli.The pattern of findings indicate that the occurrence of sleep-related attentional bias is possibly conditional.In sum,the present study suggests that the sleep-related attentional bias is not a constant trait of insomnia,which may be a expression of impairment of attention control system instead.Furthermore,it is also suggested that both sleep nature and negative emotion are closely correlated to the etiology of insomnia in term of the study findings.Those results are discussed according to previous literature and current insomnia models.Future studies in this area should replicate those findings by employing clinical sample,standard sleep-related stimuli with high ecological validity and more fine-grained design.