Sleep-related problems in highly sensitive individuals: testing the mediation effect of perceived stress

Objectives/Introduction: Sensory-processing sensitivity (SPS) is defined as an underlying phenotypic trait that describes individual differences in sensitivity to internal and external stimuli. High sensitivity is characterized by greater awareness of environmental subtleties, a tendency for over-stimulation, greater depth of information processing, and increased emotional reactivity. Thus, highly sensitive individuals are more vulnerable to stress. A recent study found that subjects scoring high on SPS reported more nightmare frequency and lower mental well-being than subjects scoring low on SPS. On this basis, we hypothesized that SPS contributes to sleep disruption and poor sleep quality and that this effect could be mediated by increased perceived stress. Methods: Two hundred eight volunteers (mean age 36.24 ± 11.18;154 females) completed the following questionnaires: the Highly Sensitive Person (HSP) scale, the Perceived Stress Scale (PSS), the Pittsburgh Sleep Quality Index (PSQI), and the Insomnia Severity Index (ISI). We considered the total score for the HSP, PSS, and ISI, while for the PSQI, the global score and its seven components. Results: Correlation analysis revealed a positive correlation between HSP and PSS, r=0.18,p<0.01. HSP was also positively correlated with ISI, r=0.26,p<0.01, and PSQI global score,r=0.19,p<0.01,as well as with PSQI components: Subjective sleep quality,r=0.17,p<0.05, Sleep latency,r=0.17,p<0.05, and Daytime dysfunction,r=0.26,p<0.01. PSS was also positively correlated with ISI, r=0.50,p<0.01, and all PSQI scores except for sleep duration, with r coefficients ranging from 0.14 to 0.37,p<0.05. We then conducted mediation analysis with HSP as antecedent variable, PSS as mediator,and ISI and PSQI as outcomes. The analysis revealed that the effect of HSP on PSS completely mediated the effect of HSP on PSQI global score,0.22,p<0.01, and on its components Subjective sleep quality,0.04,p<0.05, and Sleep latency, 0.06,p<0.05. Instead, only a partial mediation was observed for the effect of HSP on ISI, 0.48,p<0.01,and on PSQI component Daytime dysfunction, 0.03,p<0.05. Conclusions: Results supported the hypothesis that SPS correlates to increased sleep-related problems through increased perceived stress.Therefore, it is important to evaluate and further study sleep difficulties in highly sensitive individuals.