Sleep Literature Updates

Sleep Apnoea and the Brain: A Complex Relationship

Intermittent hypoxia, reoxygenation, and hypercapnia or hypocapnia occur in both adults and children during untreated apnoea and hypopnoea, along with changes in cerebral blood flow and sleep fragmentation. These effects can result in cognitive deficits with functional effects on work and school efficiency. The assessment of how obstructive sleep apnoea affects cognition depends on the specificity and sensitivity of the tests, which are rarely developed specifically for obstructive sleep apnoea. In this Review, we discuss both the neural adaptive and maladaptive processes in response to hypoxaemia. The net result on cognitive and emotional performance depends on the stage of this dynamic process, effects on other body systems, cognitive reserve, and idiosyncratic susceptibility. We also explore the contribution of fragmented sleep, and the disruption of sleep structure, with focus on the effect at different times in the development of disease. This Review will address the gap in the underlying pathophysiology of new clinical and translational findings, and argue their contribution to the inherent complexity of the association between obstructive sleep apnoea and the brain.

Effect of Melatonin on Sleep in the Perioperative Period After Breast Cancer Surgery: A Randomized, Double-Blind, Placebo-Controlled Trial

48 patients were randomized to receive 6mg melatonin or placebo for three preoperative nights, continuing into the postoperative period. As measured by actigraphy, melatonin was shown to increase sleep efficiency and decrease waking during the two weeks following surgery.

How Acute Total Sleep Loss Affects the Attending Brain: A Meta-Analysis of Neuroimaging Studies

Acute total sleep deprivation decreases brain activation in the fronto-parietal attention network (prefrontal cortex and intraparietal sulcus) and in the salience network (insula and medial frontal cortex). Increased thalamic activation after sleep deprivation may reflect a complex interaction between the de-arousing effects of sleep loss and the arousing effects of task performance on thalamic activity.

Shorter Sleep Duration is Associated with Decreased Insulin Sensitivity in Healthy White Men

Shorter sleep duration may impair insulin sensitivity and beta-cell function in nondiabetic white men, possibly contributing to later type 2 diabetes and cardiovascular disease.

Influence of Sleep Deprivation and Circadian Misalignment on Cortisol, Inflammatory Markers, and Cytokine Balance

The current findings demonstrate that total sleep deprivation and chronic circadian misalignment modulate cortisol levels and that chronic circadian misalignment increases plasma concentrations of pro- and anti-inflammatory proteins.

Altered Salience Network Connectivity Predicts Macronutrient Intake After Sleep Deprivation

Sleep deprivation has been associated with altered feeding patterns. This study reports the relationship between sleep deprivation, caloric consumption, and connectivity in affected regions of the brain. Human subjects were sleep deprived for one night, compared to the control group (normal sleep), sleep deprived individuals consumed more food during the extra wake period, and in the recovery period consumed similar total calories but with significantly more fat and less carbohydrate composition than controls. Functional MRI scanning revealed connectivity differences between the dorsal anterior cingulate cortex (dACC) and multiple regions of the brain, with the pathways between the dACC and putamen and dACC and insula being most highly correlated with increased fat and decreased carbohydrate consumption. Based on what is known of these pathways the authors suggest a connectivity mechanism by which attentiveness and reward centers (insula and putamen) interact with homeostatic-stress centers (dACC) to explain the increased consumption of fat after sleep deprivation.

Nasopharyngeal Airway Stenting Devices for Obstructive Sleep Apnoea: A Systematic Review and Meta-Analysis

In this systematic review and meta-analysis, outcomes of adults with obstructive sleep apnea treated with nasopharyngeal airway stenting devices were studied. Of 573 potential studies, 29 were retrieved for detailed evaluation and 16 met the study criteria. Only case series or case studies were identified. Short-term benefits were identified in polysomnographic indices such as the apnea-hypopnea index and oxygen saturation, especially in postoperative patients. However, long-term data with respect to patient tolerance and adherence was lacking. Future research should be directed towards designing randomized controlled trials, comparing these devices to other interventions such as CPAP, with extensive follow up and long-term clinical outcomes

The Influence of Environmental Factors on Sleep Quality in Hospitalized Medical Patients

In this prospective cohort study, 118 consecutive inpatients were screened and 99 patients were enrolled to assess sleep quality in a group of medical inpatients, in relation to environmental factors, and the switch to daylight-saving time. Thirty three percentage of the patients reported one/more sleepless nights. Patients who slept near the window were exposed to more light in the morning and tended to sleep better. Noise levels were higher than recommended for care units. Future research is needed to evaluate interventions designed to improve sleep quality for inpatients in medical and surgical wards.

Effect of Sedative-Hypnotics, Anesthetics and Analgesics on Sleep Architecture in Obstructive Sleep Apnea

This article critically reviewed the literature relevant to preoperative screening for OSA, prevalence of OSA in surgical populations and changes in postoperative sleep architecture relevant to OSA patients … in regard to the effects of sedative-hypnotics, anesthetics and analgesics on sleep architecture, the underlying mechanisms and the relevance to OSA.

A Systematic Review of Peri-Operative Melatonin

A very importat review on the use of melatonin in perioperative setting. “Qualitative reviews suggested the melatonin improved sleep quality and emergence behaviour, and might be capable of reducing oxidative stress and anaesthetic requirements.”