Source: Journal of Consulting and Clinical Psychology
Reduced adherence to psychological therapies is associated with poorer treatment outcomes in insomnia and has been identified as a barrier to treatment. Adherence to CBT can be examined using a number of different measures, nevertheless, assessing adherence can be difficult in clinical settings. Using clinical trial data, Dong and colleagues evaluated therapist ratings of patient adherence and agreement with the Adherence to Behavioural Strategies (ABS) coding grid - a measure of adherence to sleep diaries. Associations between treatment adherence, agreement and CBT outcomes were also examined. Therapist ratings of adherence were found to be positively associated with higher global ABS scores and predicted reductions in insomnia symptoms. Patient agreement with the treatment was also found to predict reductions in insomnia symptoms from pre-treatment to 6-months follow-up. Similarly, therapist-rated patient agreement, adherence and global ABS scores were predictive of insomnia remission at post-treatment, and therapist-rated adherence was the only predictor of remission at 6-months. Findings suggest therapist monitoring of patient adherence may be a simple way of determining adherence and highlights the importance of monitoring patients throughout therapy.
Unlike normal sleepers, patients with insomnia can display discrepancies between objective and self-reported estimations of sleep duration. Hyperarousal, the tendency for insomnia patients to present with increased physiological activation, may help provide an explanation for this common clinical feature. Feige and colleagues suggest microarousals experienced during REM sleep may account for subjective-objective discrepancies. Arousal thresholds were examined to understand the impact of awakenings on sleep perception in both insomnia patients (n=27) and matched normal sleepers (n=27). All underwent polysomnography over four nights, and experienced three awakenings from either Stage 2 or REM sleep on nights three and four. Results suggest waking thresholds did not differentiate between groups, however, insomnia patients reported more instances of being awake when woken from REM than normal sleepers. Reports were similar during Stage 2 sleep for both groups. Furthermore, emotionally negative mentation experienced during REM sleep was significantly stronger in insomnia patients. Thus, altered subjective reports of sleep may be associated with microarousals during REM sleep in insomnia patients.
Source: Neuroscience and Biobehavioral Reviews
Sleep disturbance may predict the occurrence of psychiatric symptoms in both clinical and non-clinical populations, however previous systematic reviews have focused only on clinical samples. Barton and colleagues aim to examine the relationship between sleep disturbance and psychotic symptoms (paranoia, delusions, hallucinations, positive and negative schizotypy), dissociation and hypomania in non-clinical populations. They found that all experiences examined were associated with some degree of sleep disturbance. Insomnia was universally associated with all psychotic, dissociative and hypomanic experiences and parasomnias correlated with psychotic experiences. Nightmare distress was associated with hypomania and psychotic symptoms with small-to-large effects; and evening chronotype was associated with dissociation and hypomania. Although many of the reviewed studies were cross-sectional, there was partial evidence of a causal link between sleep disturbance and psychotic and dissociative experiences, however effect sizes varied. This review hints at a potential causal link between sleep disturbance and psychotic symptoms in non-clinical individuals and highlights the need for future research in this area.
Source: Neurobiology of Learning and Memory.
Insomnia is associated with significant impairments to daytime functioning and includes problems with learning, emotional functioning and memory. The hippocampus is important for declarative memory formation and may be particularly sensitive to sleep loss. Previous work has suggested mixed evidence of altered connectivity and reduced hippocampal volume in insomnia patients. Leerssen and colleagues explored the relationship between sleep (polysomnography, sleep diary and questionnaire assessments) and hippocampal volume and function using brain imaging (fMRI) in insomnia patients (n=65) compared to normal sleeping controls (n=65). Insomnia patients displayed stronger functional connectivity between the hippocampus and the left middle frontal gyrus, which was associated with worse insomnia severity index scores and lower subjective sleep efficiency (diary). No differences were observed in hippocampal volume between the two groups. The authors suggest findings of increased connectivity between these regions may be associated with increased rumination given their link to the default mode network in the brain.