Sleep problem, suicide and self-harm in university students: A systematic review.

Suicide and self-harm behaviours represent public health concerns, and university students are a particularly high risk group. Identifying modifiable risk factors for the development and maintenance of suicidal thoughts and behaviours is a research priority, as prevention is crucial. Research examining the relationship between poor sleep and self-harm/suicidality within university students is, for the first time, systematically evaluated, critically appraised, and synthesised. This literature consistently demonstrates that insomnia and nightmares are associated with elevated suicide risk of suicidal thoughts and behaviours within this subpopulation of young adults. However, as findings are predominantly derived from cross-sectional investigations, the directionality of this relationship is not yet clear. While research investigating the psychological processes driving these relationships is in its infancy, preliminary findings suggest that thwarted belongingness, socio-cognitive factors and emotional dysregulation could be partly responsible. Methodological limitations are highlighted and a research agenda suggesting the key directions for future research is proposed. Continued research in this area - employing longitudinal designs, and testing novel theoretically derived hypotheses - will be crucial to the development of suicide prevention and intervention efforts.

Cross-linguistic variation in the neurophysiological response to semantic processing: evidence from anomalies at the borderline of awareness.

The N400 event-related brain potential (ERP) has played a major role in the examination of how the human brain processes meaning. For current theories of the N400, classes of semantic inconsistencies which do not elicit N400 effects have proven particularly influential. Semantic anomalies that are difficult to detect are a case in point ("borderline anomalies", e.g. "After an air crash, where should the survivors be buried?"), engendering a late positive ERP response but no N400 effect in English (Sanford, Leuthold, Bohan, & Sanford, 2011). In three auditory ERP experiments, we demonstrate that this result is subject to cross-linguistic variation. In a German version of Sanford and colleagues' experiment (Experiment 1), detected borderline anomalies elicited both N400 and late positivity effects compared to control stimuli or to missed borderline anomalies. Classic easy-to-detect semantic (non-borderline) anomalies showed the same pattern as in English (N400 plus late positivity). The cross-linguistic difference in the response to borderline anomalies was replicated in two additional studies with a slightly modified task (Experiment 2a: German; Experiment 2b: English), with a reliable LANGUAGE×ANOMALY interaction for the borderline anomalies confirming that the N400 effect is subject to systematic cross-linguistic variation. We argue that this variation results from differences in the language-specific default weighting of top-down and bottom-up information, concluding that N400 amplitude reflects the interaction between the two information sources in the form-to-meaning mapping.

The processing of good-fit semantic anomalies: an ERP investigation.

The failure-to-detect good-fit semantic anomalies is taken as evidence for shallow semantic processing, however the cognitive mechanisms involved are not well understood. To investigate this we recorded event-related potentials (ERPs) to sentences that contained good and poor-fit semantic anomalies and non-anomalous controls. Detected good-fit anomalies elicited an N400 effect when detection accuracy was stressed, indicating the registration of the anomaly. ERP analyses further ruled out that anomaly non-/detection is due to differences in initial word encoding or in processing prior contextual information. In addition, starting in the P2 interval, the ERP waveform was less positive for non-detected than detected anomalies and non-anomalous controls, presumably reflecting a language-driven modulation of visual input processing. And finally, detection of good-fit anomalies may also depend on the integration of sentential information into the discourse model at the end of the critical sentence. Overall, present findings support the shallow processing account of anomaly detection failure.

Anomalies at the borderline of awareness: an ERP study.

Behaviorally, some semantic anomalies, such as those used to demonstrate N400 effects in ERPs, are easy to detect. However, some, such as "after an air crash, where should the survivors be buried?" are difficult. The difference has to do with the extent to which the anomalous word fits the general context. We asked whether anomalies that are missed elicit an ERP that could be taken as indicating unconscious recognition, and whether both types elicit an N400 effect when they are detected. We found that difficult anomalies having a good fit to general context did not produce an N400 effect, whereas control "easy-to-detect" anomalies did. For difficult anomalies, there was no evidence for unconscious detection occurring. The results support a qualitative distinction in the way the two types of anomalies are processed, and the idea that semantic information is simply not utilized (shallow processing) when difficult anomalies are missed.

Semantic anomalies at the borderline of consciousness: an eye-tracking investigation.

We report an eye-tracking study in which participants read passages containing difficult-to-detect semantic anomalies. Would there be any evidence of the registration of the anomaly within the comprehension system (reflected in eye tracking) when anomalies were not noticed? Using early and late processing measures, there was no evidence for registration independent of conscious detection. Comparisons were made between detected and undetected anomalies and between these and nonanomalous controls. There was evidence of disruption to the tracking measures only when a conscious report was also made. These data fit the view that shallow semantic processing underlies the failure to detect anomalies. Implications for language processing are discussed.