The Relationship Between Negative Life Events,Psychological Capital,and Sleep Quality In Adolescents From The Matching Perspective

Background:Adolescent sleep quality problems have become an urgent public health issue and one of the student health problems that health professionals in secondary schools need to address.It is critical to identify modifiable factors influencing sleep quality to promote sleep health in adolescents.Existing studies have analyzed the moderating effect of psychological capital on the relationship between negative life events and sleep quality,but have not yet reflected relative differences in the actual levels of sleep quality of individuals with different levels of negative life events and psychological capital.Currently,researchers in the fields of organization and management and personality and social psychology have developed theories and methods for analyzing the effects of two independent variables on a dependent variable based on the matching perspective,providing a new approach to explore the relative differences in the actual levels of sleep quality of individuals with different levels of negative life events and psychological capital.Therefore,this study aimed to investigate the relationship between negative life events,psychological capital,and sleep quality based on the matching perspective.Methods:This study was cross-sectional.Convenient sampling was used to select students studying at a public high school in Lanzhou City from April to May 2022 as the research subjects.The sleep quality of adolescents was measured using the Pittsburgh Sleep Quality Index(a higher score indicates worse sleep quality).The Adolescent Life Events Scale was used to assess negative life events(a higher score indicates higher levels of negative life events),and the Psychological Capital Questionnaire was used to assess adolescents’psychological capital(a higher score indicates higher levels of psychological capital).Firstly,the negative life events and psychological capital scores were unified to the same scale(i.e.,0～6)and then centralized.Then polynomial regression combined with response surface analysis was used to explore the relationship between negative life events-psychological capital matching and sleep quality.Statistical analyses were carried out using SPSS 26.0 software,and the significance level was set at α=0.05.Results:There was a quadratic relationship between negative life events and sleep quality scores(B=-0.17,SE=0.04,P<0.001),showing that adolescents had the worst sleep quality when experiencing nearly moderate levels of negative life events.Psychological capital was significantly and negatively associated with sleep quality scores(B=-0.59,SE=0.09,P<0.001),The slope of the response surface along the consistency line was statistically significant and negative(α1=-0.45;95%CI=-0.72,-0.21),but the curvature was nonsignificant(α2=-0.12;95%CI=-0.35,0.13),showing that when the levels of negative life events and psychological capital were equal,sleep quality scores increased(i.e.,sleep quality worsened)as the levels of both negative life events and psychological capital decreased.Besides,the slope(α3=0.72;95%CI=0.50,0.95)and curvature(α4=-0.15;95%CI=-0.29,-0.03)of the response surface along the inconsistency line were both statistically significant and the curvature was negative,showing a concave response surface along the inconsistency line.The z-hat test showed that the sleep quality was worse when "the level of negative life events was higher than that of psychological capital" than when "the level of negative life events was lower than that of psychological capital"(z-hatdifference=1.92;95%CI=1.55,2.28).Conclusions:There was a U-shaped relationship between negative life events and sleep quality.Specifically,adolescents had the worst sleep quality when experiencing nearly moderate levels of negative life events.Psychological capital was a protective factor for sleep quality.When the levels of negative life events and psychological capital were equal,the lower the levels,the worse the sleep quality.Adolescents had worse sleep quality when the level of negative life events was higher than that of psychological capital than when the level of negative life events was lower than that of psychological capital.