A structural equation model of the relationship between insomnia, negative affect, and paranoid thinking

BACKGROUND: A growing body of evidence points to relationships between insomnia, negative affect, and paranoid thinking. However, studies are needed to examine (i) whether negative affect mediates the relation between insomnia and paranoid thinking, (ii) whether different types of insomnia exert different effects on paranoia, and (iii) to compare the impact of objective and self-reported sleeping difficulties. METHOD: Structural equation modelling was therefore used to test competing models of the relationships between self-reported insomnia, negative affect, and paranoia. n = 348 participants completed measures of insomnia, negative affect and paranoia. A subset of these participants (n = 91) went on to monitor their sleep objectively (using a portable sleep monitor made by Zeo) for seven consecutive nights. Associations between objectively recorded sleep, negative affect, and paranoia were explored using linear regression. RESULTS: The findings supported a fully mediated model where self-reported delayed sleep onset, but not self-reported problems with sleep maintenance or objective measures of sleep, was directly associated with negative affect that, in turn, was associated with paranoia. There was no evidence of a direct association between delayed sleep onset or sleep maintenance problems and paranoia. CONCLUSIONS: Taken together, the findings point to an association between perceived (but not objective) difficulties initially falling asleep (but not maintaining sleep) and paranoid thinking; a relationship that is fully mediated by negative affect. Future research should seek to disentangle the causal relationships between sleep, negative affect, and paranoia (e.g., by examining the effect of an intervention using prospective designs that incorporate experience sampling). Indeed, interventions might profitably target (i) perceived sleep quality, (ii) sleep onset, and / or (iii) emotion regulation as a route to reducing negative affect and, thus, paranoid thinking

Does improving sleep lead to better mental health? A protocol for a meta-analytic review of randomised controlled trials

INTRODUCTION: Sleep and mental health go hand-in-hand, with many, if not all, mental health problems being associated with problems sleeping. Although sleep has been traditionally conceptualised as a secondary consequence of mental health problems, contemporary views prescribe a more influential, causal role of sleep in the formation and maintenance of mental health problems. One way to evaluate this assertion is to examine the extent to which interventions that improve sleep also improve mental health. METHOD AND ANALYSIS: Randomised controlled trials (RCTs) describing the effects of interventions designed to improve sleep on mental health will be identified via a systematic search of four bibliographic databases (in addition to a search for unpublished literature). Hedges' g and associated 95% CIs will be computed from means and SDs where possible. Following this, meta-analysis will be used to synthesise the effect sizes from the primary studies and investigate the impact of variables that could potentially moderate the effects. The Jadad scale for reporting RCTs will be used to assess study quality and publication bias will be assessed via visual inspection of a funnel plot and Egger's test alongside Orwin's fail-safe n. Finally, mediation analysis will be used to investigate the extent to which changes in outcomes relating to mental health can be attributed to changes in sleep quality. ETHICS AND DISSEMINATION: This study requires no ethical approval. The findings will be submitted for publication in a peer-reviewed journal and promoted to relevant stakeholders. PROSPERO REGISTRATION NUMBER: CRD42017055450

The effect of an online self-help cognitive behavioural intervention for insomnia on negative affect and paranoia: a randomised controlled trial

Background: Sleep and mental health go hand-in-hand, with problems sleeping being associated with a variety of mental health difficulties. Recently, insomnia has been linked with the experience of paranoia, a relationship that is likely to be mediated by negative affect. Given these links, the present research aimed to test whether a self-help intervention designed to improve sleep can also improve negative affect and paranoia. Method: Participants were recruited from a mailing list of University staff and were randomly allocated to one of three conditions; a wait-list control group, an active control group who completed a sleep diary each day for 6 weeks, and an experimental group who received an online self-help intervention targeting sleep problems alongside the same sleep diary. Levels of insomnia, negative affect, and paranoia were measured at baseline, immediately post-intervention, and 4- and 18-weeks post-intervention. Results: There were no significant differences between the groups on levels of insomnia, negative affect, and/or paranoid thinking at post-intervention, 4-weeks, or the 18-week follow-up. However, a relatively large number of participants dropped out of the study, particularly in the intervention group, which meant that the primary analysis was underpowered. Conclusion: Due to a high level of participant dropout, the findings from the present research are inconclusive, and suggest that retaining participants in trials of online interventions is a significant challenge that needs to be addressed in future research

Ytterbium doped nano-crystalline optical fiber for reduced photodarkening

We report suppression of photodarkening in Yb-doped nano-crystalline fibers in silica host. The photodarkening induced loss reduced by 20 times compared to Yb-doped aluminosilicate fibers. The laser efficiency of the nano-crystalline fiber was 79%

Temperature dependence of non-linear electrical conduction behavior in a screen-printed multi-component nanocomposite

Nanocomposite materials are of growing applications importance in many areas, particularly touch sensitive surfaces. Here, current-voltage measurements were performed over a range of temperatures and static compressive loadings on a new variant of a multi-component, screen-printed nanocomposite ink, in order to understand the physical nature of the electrical transport behavior. A physical model, combining a linear percolative electrical conductance and a highly non-linear conductance, that is ascribed to field assisted quantum tunneling, was successful in describing the temperature dependence of the I-V. This provides a theoretical underpinning for conduction in these functional nanocomposites

Optical fiber fabrication using novel gas-phase deposition technique

We report a highly versatile chemical-in-crucible preform fabrication technique suitable for gas-phase deposition of doped optical fibers. Aluminosilicate and ytterbium-doped phosphosilicate fibers are presented demonstrating the technique and its potential for realizing complex fiber designs that are suitable for the next generation of high-power fiber devices. The results show aluminum-doped fiber with numerical aperture of 0.28 and ytterbium-doped fiber with a measured slope efficiency of 84% with respect to pump launch power

Vapor sensing properties of a conductive polymer composite containing Nickel particles with nano-scale surface features

This paper presents an unusual conductive polymer composite, produced by Peratech Ltd under the trademark QTC™, which has many vapor sensing applications. Nickel particles are intimately coated by an elastomeric binder such that no percolative conduction can occur. However, the nickel particles are shown to possess spiky nanoscale surface features, which promote conduction by a field-assisted quantum tunneling mechanism. Granular QTC™ can be dispersed into a polymer matrix to produce a vapor sensor. Under exposure to vapor, the polymer swells and the resistance of the composite increases. In this work, granular sensors are subjected to acetone and tetrahydrofuran (THF) vapors. The response for THF shows an increase in resistance of a factor of 108, over a time-scale of a few seconds. This response is larger and faster than many conventional vapor sensing composites. This is a significantly larger response than that obtained historically for the same sensor, suggesting that some degree of sensor aging is desirable. The response and subsequent recovery can be explained by a case II diffusion model, and linked to Hildebrand solubility parameters of the vapor and polymer components