Normal sleep and circadian processes

Development of a biomathematical model for human alertness and fatigue risk assessment based on the concept of energy

Fatigue risk in humans has few biomathematical models, and existing biomathematical models have many shortcomings. We developed a biomathematical model of fatigue risk based on the concept of energy to quantify human alertness from the perspective of energy and used alertness to characterise human psychological fatigue risk. The model allows mathematical modelling of activity processes that concern sleep intensity and quality and distinguishes between intrinsic exertion in the waking state and workload exertion in the workload state. This alertness and fatigue risk biomathematical model predicts changes in human alertness and fatigue risk indices at any point in the day. We applied numerical simulation and model analysis to five cases to validate the potential value of the alertness energy fatigue risk biomathematical model. Practitioner summary: To overcome the shortcomings of current biomathematical models that evaluate fatigue risk, this study developed a biomathematical model of fatigue risk based on the concept of energy to quantify human alertness from the perspective of energy and used alertness to characterise human fatigue risk.Abbreviations: S: The sleep homeostatic process; C: The circadian process; SAFTE: The sleep activity fatigue and task effectiveness model; FAID: The fatigue audit interdyne model; EEG: Electroencephalogram.

Validated Wearable Device Shows Acute Postoperative Changes in Sleep Patterns Consistent With Patient-Reported Outcomes and Progressive Decreases in Device Compliance After Shoulder Surgery

Purpose

To assess the utility of a validated wearable device (VWD) in examining preoperative and postoperative sleep patterns and how these data compare to patient-reported outcomes (PROs) after rotator cuff repair (RCR) or total shoulder arthroplasty (TSA).

Methods

Male and female adult patients undergoing either RCR or TSA were followed up from 34 days preoperatively to 6 weeks postoperatively. Sleep metrics were collected using a VWD in an unsupervised setting. PROs were assessed using the following validated outcome measures: Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function questionnaire; American Shoulder and Elbow Surgeons self-evaluation questionnaire; visual analog scale assessing pain; and Disabilities of the Arm, Shoulder and Hand questionnaire. Data were analyzed preoperatively and at 2-week intervals postoperatively with χ2 analysis to evaluate device compliance. Sleep metrics and PROs were evaluated at each interval relative to preoperative values within each surgery type with an analysis of variance repeated on time point. The relation between sleep metrics and PROs was assessed with correlation analysis.

Results

A total of 57 patients were included, 37 in the RCR group and 20 in the TSA group. The rate of device compliance in the RCR group decreased from 84% at surgery to 46% by 6 weeks postoperatively (P < .001). Similarly, the rate of device compliance in the TSA group decreased from 81% to 52% (P < .001). Deep sleep decreased in RCR patients at 2 to 4 weeks (decrease by 10.99 ± 3.96 minutes, P = .021) and 4 to 6 weeks postoperatively (decrease by 13.37 ± 4.08 minutes, P = .008). TSA patients showed decreased deep sleep at 0 to 2 weeks postoperatively (decrease by 12.91 ± 5.62 minutes, P = .045) and increased rapid eye movement sleep at 2 to 4 weeks postoperatively (increase by 26.91 ± 10.70 minutes, P = .031). Rapid eye movement sleep in the RCR group and total sleep in the TSA group were positively correlated with more favorable PROs (P < .05).

Conclusions

VWDs allow for monitoring components of sleep that offer insight into potential targets for improving postoperative fatigue, pain, and overall recovery after shoulder surgery. However, population demographic factors and ease of device use are barriers to optimized patient compliance during data collection.

Level of Evidence

Level IV, diagnostic case series.

REM-OSA as a Tool to Understand Both the Architecture of Sleep and Pathogenesis of Sleep Apnea-Literature Review

Sleep is a complex physiological state, which can be divided into the non-rapid eye movement (NREM) phase and the REM phase. Both have some unique features and functions. This difference is best visible in electroencephalography recordings, respiratory system activity, arousals, autonomic nervous system activity, or metabolism. Obstructive sleep apnea (OSA) is a common condition characterized by recurrent episodes of pauses in breathing during sleep caused by blockage of the upper airways. This common condition has multifactorial ethiopathogenesis (e.g., anatomical predisposition, sex, obesity, and age). Within this heterogenous syndrome, some distinctive phenotypes sharing similar clinical features can be recognized, one of them being REM sleep predominant OSA (REM-OSA). The aim of this review was to describe the pathomechanism of REM-OSA phenotype, its specific clinical presentation, and its consequences. Available data suggest that in this group of patients, the severity of specific cardiovascular and metabolic complications is increased. Due to the impact of apneas and hypopneas predominance during REM sleep, patients are more prone to develop hypertension or glucose metabolism impairment. Additionally, due to the specific function of REM sleep, which is predominantly fragmented in the REM-OSA, this group presents with decreased neurocognitive performance, reflected in memory deterioration, and mood changes including depression. REM-OSA clinical diagnosis and treatment can alleviate these outcomes, surpassing the traditional treatment and focusing on a more personalized approach, such as using longer therapy of continuous positive airway pressure or oral appliance use.

Improve sleep in critically ill patients: Study protocol for a randomized controlled trial for a multi-component intervention of environment control in the ICU

INTRODUCTION

In critically ill patients, sleep and circadian rhythms are greatly altered. These disturbances have been associated with adverse consequences, including increased mortality. Factors associated with the ICU environment, such as exposure to inadequate light and noise levels during the day and night or inflexible schedules of daily care activities, have been described as playing an essential role in sleep disturbances. The main objective of this study is to evaluate the impact of the use of a multifaceted environmental control intervention in the ICU on the quantity and quality of sleep, delirium, and post-intensive care neuropsychological impairment in critically ill patients.

METHODS

This is a prospective, parallel-group, randomized trial in 56 critically ill patients once they are starting to recover from their acute illness. Patients will be randomized to receive a multifaceted intervention of environmental control in the ICU (dynamic light therapy, auditory masking, and rationalization of ICU nocturnal patient care activities) or standard care. The protocol will be applied from enrollment until ICU discharge. Baseline parameters, light and noise levels, polysomnography and actigraphy, daily oscillation of plasma concentrations of Melatonin and Cortisol, and questionnaires for the qualitative evaluation of sleep, will be assessed during the study. In addition, all patients will undergo standardized follow-up before hospital discharge and at 6 months to evaluate neuropsychological impairment.

DISCUSSION

This study is the first randomized clinical trial in critically ill patients to evaluate the effect of a multicomponent, non-pharmacological environmental control intervention on sleep improvement in ICU patients. The results will provide data about the potential synergistic effects of a combined multi-component environmental intervention in ICU on outcomes in the ICU and long term, and the mechanism of action.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT. Registered on January 10, 2023. Last updated on 24 Jan 2023.

Relationship Between Episodic Nocturnal Hypercapnia and History of Exacerbations in Patients with Advanced Chronic Obstructive Pulmonary Disease

Purpose

An episodic increase in transcutaneous carbon dioxide pressure (PtcCO₂) is often recognized in patients with advanced chronic obstructive pulmonary disease (COPD) by overnight PtcCO₂ monitoring. This phenomenon, called episodic nocturnal hypercapnia (eNH), mainly corresponds to rapid eye movement (REM) sleep-related hypoventilation. However, it is unclear whether eNH is associated with the frequency of COPD exacerbation. We aimed to investigate whether a relationship exists between COPD exacerbation and eNH.

Patients and Methods

We enrolled consecutive patients with stable, severe, or very severe COPD with a daytime arterial carbon dioxide pressure (PaCO₂) <55.0 mmHg who underwent overnight PtcCO₂ monitoring from April 2013 to January 2017. We retrospectively analyzed the prevalence of eNH and sleep-associated hypoventilation (SH) as defined by the American Academy of Sleep Medicine. Moreover, we compared the relationship between the frequency of COPD exacerbations in the previous year and eNH or SH.

Results

Twenty-four patients were included in this study. The study patients had a mean daytime PaCO₂ and nocturnal PtcCO₂ of 43.3 ± 6.8 mmHg and 42.9 ± 9.6 mmHg, respectively. Six (25.0%) and 11 (45.9%) of the 24 patients met the SH and eNH criteria, respectively. The odds ratios of SH and eNH for at least one annual exacerbation were 1.0 [95% confidence interval (CI): 0.16–6.00] and 11.1 [95% CI: 1.39–87.7], respectively. The odds ratios of SH and eNH for at least two annual exacerbations were 0.3 [95% CI: 0.04–2.64] and 6.6 [95% CI: 1.06–39.4], respectively.

Conclusion

In patients with advanced COPD and a daytime PaCO₂ <55.0 mmHg, eNH may be associated with a history of more frequent exacerbations than SH. Further studies are required to validate these findings.

The Effect of Change of Working Schedule on Health Behaviors: Evidence from the Korea Labor and Income Panel Study (2005–2019)

This study investigated whether changes in work schedule are associated with health behavior changes. We used data from the Korea Labor and Income Panel Survey from 2005 to 2019. A generalized estimating equation model was used to assess the association between changes of work schedules (day–day, day–shift, shift–day, and shift–shift) and health behaviors. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated after adjusting for general and socioeconomic characteristics. Fixed daytime work was observed for 25,716 person-years, and fixed shift work was observed for 2370 person-years out of the total 4046 participants during a 14 year period. Workers who changed their work schedule from fixed daytime to shift work and from shift to fixed daytime work contributed to 670 and 739 person-years, respectively. Considering continuous fixed daytime workers as a reference group, continuous exposure to shift work (aOR 1.11, CI 1.01–1.26) and changes from fixed daytime to shift work (aOR 1.18, CI 1.05–1.44) were significantly associated with an increased risk of changing either smoking or drinking behavior to unhealthy patterns. The results of our study suggest that workers who work irregular shift times, in contrast to those with more standard, regular work schedules, are at a higher risk of changing smoking and/or drinking behavior to unhealthy patterns.

Sleep architecture of short sleep time in patients with obstructive sleep apnea: a retrospective single-facility study

PURPOSE

Sleep architecture consists of rapid eye movement (REM) sleep and non-REM sleep time. Non-REM sleep time is further classified into three stages by depth (stage N1-N3). Some studies have reported that short sleep time predicts all-cause mortality. Short sleep time can have characteristics of sleep architecture which contribute to poor prognosis. Obstructive sleep apnea (OSA) is a disease which causes cessation or decline of ventilation during sleep due to upper airway stenosis and affects sleep architecture. Few studies have reported on the sleep architecture of short sleep time in patients with OSA. Therefore, we aimed to observe this phenomenon.

METHODS

From May 2008 to September 2021, patients diagnosed with OSA at our facility were assessed for clinical history and underwent full-night polysomnography (PSG). These patients were classified into two groups: total sleep time (TST) recorded on PSG consisting of a short TST (< 7 h) group and a not short TST (≥ 7 h) group.

RESULTS

Of 266 patients with OSA, compared to the not short TST group (n = 131), the short TST group (n = 135) had a lower REM sleep time (%) and a higher stage N1 sleep time (%). There was a significant difference in age between the two groups, so sub-analyses classified the patients by age: non-elderly patients (< 65 years) and elderly patients (≥ 65 years) to adjust for age. Both sub-analyses showed similar results to the analysis for the combined ages regarding sleep architecture.

CONCLUSION

Patients with OSA who had short sleep time had disordered sleep architecture with a lower REM sleep time (%) and more stage N1 sleep time.

Sleep Disruption Worsens Seizures: Neuroinflammation as a Potential Mechanistic Link

Sleep disturbances, such as insomnia, obstructive sleep apnea, and daytime sleepiness, are common in people diagnosed with epilepsy. These disturbances can be attributed to nocturnal seizures, psychosocial factors, and/or the use of anti-epileptic drugs with sleep-modifying side effects. Epilepsy patients with poor sleep quality have intensified seizure frequency and disease progression compared to their well-rested counterparts. A better understanding of the complex relationship between sleep and epilepsy is needed, since approximately 20% of seizures and more than 90% of sudden unexpected deaths in epilepsy occur during sleep. Emerging studies suggest that neuroinflammation, (e.g., the CNS immune response characterized by the change in expression of inflammatory mediators and glial activation) may be a potential link between sleep deprivation and seizures. Here, we review the mechanisms by which sleep deprivation induces neuroinflammation and propose that neuroinflammation synergizes with seizure activity to worsen neurodegeneration in the epileptic brain. Additionally, we highlight the relevance of sleep interventions, often overlooked by physicians, to manage seizures, prevent epilepsy-related mortality, and improve quality of life.

Disruption of Circadian Rhythms and Gut Motility: An Overview of Underlying Mechanisms and Associated Pathologies

Circadian rhythms ensure that physiological processes occur at the most biologically meaningful time. The circadian timing in the gastrointestinal tract involves interlocking transcriptional and translational feedback loops that culminate in the rhythmic expression and activity of a set of clock genes and related hormones. The suprachiasmatic nucleus and peripheral core molecular clocks oscillate every 24 hours and are responsible for the periodic activity of various segments and transit along the gastrointestinal tract. Environmental cues may alter or reset these rhythms to align them with new circumstances. Colonic motility also follows a circadian rhythm with reduced nocturnal activity. Healthy humans have normal bowel motility during the day, frequently following awakening or following a meal, with minimal activity during the night. Maladjusted circadian rhythms in the bowel have been linked to digestive pathologies, including constipation and irritable bowel syndrome. Our advanced knowledge of the link between the circadian clock and gastrointestinal physiology provides potential therapeutic approaches for the treatment of gastrointestinal diseases. This review seeks to establish evidence for the correlation between circadian rhythm, bowel movements and digestive health, and examine the implications of disrupted circadian rhythms on gut physiology.

Nighttime Sleep Duration Is Associated With Length of Stay Outcomes Among Older Adult Survivors of Critical Illness

BACKGROUND

Older adults who required mechanical ventilation while in an intensive care unit (ICU) require adequate sleep throughout recovery from critical illness. Poor post-ICU sleep quality may contribute to worsening impairments in physical, cognitive, or psychological status after critical illness, known as post-ICU syndrome. Previous research has evaluated post-ICU sleep with qualitative or mixed methods (eg, interviews, questionnaires). We proposed measurement of sleep with actigraphy. We hypothesized that nighttime sleep is associated with length of stay (LOS).

OBJECTIVES

The aims of this study were to describe sleep quality of previously mechanically ventilated older adults recently transferred out of ICU and explore relationships between sleep duration and LOS outcomes.

METHODS

We enrolled 30 older adults, 65 years and older, within 24 to 48 hours after ICU discharge. We collected actigraphy data on post-ICU sleep duration (total sleep time [TST]) and sleep fragmentation (wake time after sleep onset) over 2 consecutive nights. We explored associations between TST and LOS (in days) outcomes using multivariate regression.

RESULTS

Subjects' mean TST was 7.55 ± 2.52 hours, and mean wake time after sleep onset was 2.26 ± 0.17 hours. In exploratory regression analyses, longer ICU LOS (β = 0.543, P < .001) and longer length of mechanical ventilation (β = 0.420, P = .028) were associated with greater post-ICU TST, after adjusting for potential confounding factors. Total sleep time was prospectively associated with total hospital LOS (β = 0.535, P < .001).

DISCUSSION

Older ICU survivors demonstrate greater sleep duration and worse sleep fragmentation. Poor sleep may contribute to longer LOS, secondary to post-ICU syndrome and sequelae. We recommend nursing interventions to promote sleep consolidation throughout transitions of care in the acute post-ICU recovery period.

Assessing the impacts of ALAN and noise proxies on sleep duration and quality: evidence from a nation-wide survey in Israel

Sleep is a reversible state that sustains physiological and psychological processes in humans. As well established, individual-level factors, such as stress, smoking, drugs, and caffeine intake, reduce sleep duration and quality. However, studies of the effect of environmental risk factors, such as artificial light at night (ALAN) and noise, on sleep have been infrequent. Using records obtained from the 2017 Social Survey of Israel and combined with ALAN satellite data and various proxies for traffic noise, the present study aimed to determine how the combination of ALAN and traffic noise impact sleep duration and quality in urban areas. The increase of road density at the place of residence reduces average sleep duration by ~4.5% (~18 min.) and increases the frequency of reported sleep difficulties by ~3.5%, all other factors held equal. Similarly, an increase in ALAN exposure reduces average sleep duration by ~3% (~12 min) and increases the frequency of reported sleep difficulties by ~11%. The study also reveals a significant interaction between the two environmental risk factors in question, with the adverse impact of ALAN on sleep quality especially pronounced in high noise exposure areas.

Influence of rapid eye movement sleep on all-cause mortality: a community-based cohort study

Introduction: Although the proportion and duration of rapid eye movement (REM) sleep are correlated with neurological and cardiovascular diseases, whether REM sleep is associated with all-cause mortality in community-based populations remains unknown.

Methods: A prospective study was performed within the Sleep Heart Health Study (SHHS, Registration NO. NCT00005275). Total sleep time, sleep efficiency, and REM sleep were measured using polysomnography. Cox proportional hazards regression models were used to estimate the association of the REM sleep with all-cause mortality.

Results: Over a mean follow-up period of 11.0 ± 3.1 y, 1234 individuals (21.9%) died. In the entire population, reduced REM sleep was significantly associated with increasing all-cause mortality. After adjustment for age, sex, race, body mass index, smoking status, total cholesterol, triglycerides, high-density lipoprotein, history of diabetes and hypertension, and the apnea–hypopnea index, the duration and proportion of REM sleep were found to be significantly associated with all-cause mortality when the lowest and the highest REM quartile groups were compared (hazard ratio, 95% confidence interval: 1.727, 1.434-2.079; 1.545, 1.298-1.839; respectively).

Conclusion: The proportion and duration of REM sleep are negatively associated with all-cause mortality. This finding emphasizes the importance of personalized sleep management in community-based populations.

Sleep and Circadian Rhythm in Critical Illness

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2019. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2019 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901 .

Sleep Quality and Quantity in Intensive Care Unit Patients: A Cross-sectional Study

Introduction:

Lack of restorative sleep and altered sleep-wake cycle is a frequent problem among patients admitted to the Intensive Care Unit (ICU). This study was conducted to estimate the prevalence of poor sleep and patient's perspective of factors governing poor sleep in the ICU.

Materials and Methods:

A cross-sectional study was performed in medical ICU of a tertiary care hospital. A total of 32 patients admitted to the ICU for at least 24 h were recruited. A 72-h actigraphy was done followed by a subjective assessment of sleep quality by the Richards-Campbell Sleep Questionnaire (RCSQ). Patient's perspective of sleep quality and quantity and possible risk factors for poor sleep were recorded.

Results:

Poor sleep (defined as RCSQ <50, sensitivity 88% and specificity 87%) was found in 15 out of the 32 patients (47%). The prevalence of poor sleep was higher among patients on mechanical ventilation (n = 15) (66.7% vs. 33.3%, P < 0.05). Patients with poor sleep had higher age (median age [in years] 42.8 vs. 31.4, P = 0.008), acute physiology, and chronic health evaluation II score (mean 14 ± 5.15 vs. 9.3 ± 5.64, P = 0.02), SAPS 3 score (62.7 ± 8.9 vs. 45.6 ± 10.5, P ≤ 0.0001), and worse actigraphy parameters. Only 55.63% of total sleep time was in the night (2200–0600). All patients had discomfort from indwelling catheters and suctioning of endotracheal tubes. All patients suggested that there be a minimum interruption in the sleep for interventions or medications.

Conclusion:

There is a high prevalence of poor sleep among patients admitted to the ICU. There is a dire need to minimize untimely interventions and design nonpharmacological techniques to allow patients to sleep comfortably.

Sleep complaints in older blacks: do demographic and health indices explain poor sleep quality and duration?

OBJECTIVE

To examine the relationship between measures of sleep quality and the presence of commonly encountered comorbid and sociodemographic conditions in elderly Black subjects.

METHOD

Analyses included participants from the Baltimore Study of Black Aging (BSBA; n = 450; mean age 71.43 years; SD 9.21). Pittsburgh Sleep Quality Index (PSQI) measured overall sleep pattern and quality. Self-reported and objective measures of physical and mental health data and demographic information were collected for all participants.

RESULTS

Sociodemographic and comorbid health factors were significantly associated with sleep quality. Results from regression analyses revealed that older age, current financial strain, interpersonal problems, and stress were unique predictors of worse sleep quality. Sleep duration was significantly correlated with age, depressive affect, interpersonal problems, and stress; only age was a unique significant predictor. While participants 62 years or younger had worse sleep quality with increasing levels of stress, there was no significant relationship between sleep quality and stress for participants 81 years and older.

CONCLUSIONS

Several potential mechanisms may explain poor sleep in urban, community dwelling Blacks. Perceived stressors, including current financial hardship or hardship experienced for an extended time period throughout the lifespan, may influence sleep later in life.

Racial differences in self-reports of short sleep duration in an urban-dwelling environment

OBJECTIVES

To explore whether there are differences in sleep duration between blacks and whites residing in similar urban neighborhoods and examine whether the relationship between sleep durations and sociodemographic and/or health indices are consistent for blacks and whites.

METHODS

A total of 1,207 participants from the Healthy Aging in Neighborhoods of Disparities across the Life Span study (age: mean = 47, standard deviation = 8.74). Sleep duration was assessed by a self-report of hours of nightly sleep in the past month. Sociodemographic measures included age, sex, education, poverty status, and perceived neighborhood disorder. Health status was assessed using measures of vigilance, depression, perceived stress, coronary artery disease, diabetes, blood pressure, and inflammation.

RESULTS

There were no significant racial group differences in sleep duration. Whites, however, were more likely than blacks to report sleep durations of <6/6-7 hr compared with >7 hr with increasing stress and education levels. Blacks were more likely than whites to report short sleep durations (i.e., 6-7 hr vs. >7 hr of sleep) with increasing inflammation levels.

DISCUSSION

Although racial disparities in sleep duration are minimized when the environment is equivalent between blacks and whites, the underlying demographic and health explanations for short sleep durations may vary between whites and blacks.

Adolescents and young adults with Down syndrome presenting to a medical clinic with depression: co-morbid obstructive sleep apnea

Adolescents and young adults with Down syndrome (DS) sometimes experience new-onset mood disorder and decline in adaptive skills. The clinical phenomenon is poorly characterized and its pathogenesis is not understood. The possible contribution of obstructive sleep apnea syndrome (OSAS) to this phenomenon has not been studied. Subjects were ascertained as a convenience sample through our clinic for persons with DS and medical or mental health concerns between 2004 and 2009. When mood symptoms were present an axis I diagnosis was made using DSM-IV-R criteria. Subjects without an axis I diagnosis served as controls. The Reiss scales for children's dual diagnosis and the aberrant behavior checklist (ABC) were completed by caretakers. Twenty-eight cases meeting criteria for major depressive episode (MDE) and nine controls without psychopathology were referred for overnight polysomnography (PSG). Functional decline was reported in 19 (68%) of cases with MDE, but none of the controls. Twenty-four (86%) cases had OSAS compared with only 4 (44%) of controls. Moderate-severe OSAS was present in 15 (54%) of cases compared to only 1 (11%) of controls. Intermittent sleep-associated hypoxia and REM sleep deficits were also more frequent in cases. Across all subjects, prior tonsillectomy was not related to the presence or absence of OSAS. Our findings suggest that OSAS may be a common co-morbidity in adolescents and younger adults with DS and depression. Recognition of this association maybe critical to understanding the pathogenesis and management of mood-related disorders, and functional decline in affected individuals.

Sedation for critically ill or injured adults in the intensive care unit: a shifting paradigm

As most critically ill or injured patients will require some degree of sedation, the goal of this paper was to comprehensively review the literature associated with use of sedative agents in the intensive care unit (ICU). The first and selected latter portions of this article present a narrative overview of the shifting paradigm in ICU sedation practices, indications for uninterrupted or prolonged ICU sedation, and the pharmacology of sedative agents. In the second portion, we conducted a structured, although not entirely systematic, review of the available evidence associated with use of alternative sedative agents in critically ill or injured adults. Data sources for this review were derived by searching OVID MEDLINE and PubMed from their first available date until May 2012 for relevant randomized controlled trials (RCTs), systematic reviews and/or meta-analyses and economic evaluations. Advances in the technology of mechanical ventilation have permitted clinicians to limit the use of sedation among the critically ill through daily sedative interruptions or other means. These practices have been reported to result in improved mortality, a decreased length of ICU and hospital stay and a lower risk of drug-associated delirium. However, in some cases, prolonged or uninterrupted sedation may still be indicated, such as when patients develop intracranial hypertension following traumatic brain injury. The pharmacokinetics of sedative agents have clinical importance and may be altered by critical illness or injury, co-morbid conditions and/or drug-drug interactions. Although use of validated sedation scales to monitor depth of sedation is likely to reduce adverse events, they have no utility for patients receiving neuromuscular receptor blocking agents. Depth of sedation monitoring devices such as the Bispectral Index (BIS©) also have limitations. Among existing RCTs, no sedative agent has been reported to improve the risk of mortality among the critically ill or injured. Moreover, although propofol may be associated with a shorter time to tracheal extubation and recovery from sedation than midazolam, the risk of hypertriglyceridaemia and hypotension is higher with propofol. Despite dexmedetomidine being linked with a lower risk of drug-associated delirium than alternative sedative agents, this drug increases risk of bradycardia and hypotension. Among adults with severe traumatic brain injury, there are insufficient data to suggest that any single sedative agent decreases the risk of subsequent poor neurological outcomes or mortality. The lack of examination of confounders, including the type of healthcare system in which the investigation was conducted, is a major limitation of existing pharmacoeconomic analyses, which likely limits generalizability of their results.

Sleep disturbances in critically ill patients in ICU: how much do we know?

Sleep disturbances in the intensive care unit (ICU) seem to lead to development of delirium, prolonged ICU stay, and increased mortality. That is why sufficient sleep is important for good outcome and recovery in critically ill patients. A variety of small studies reveal pathological sleep patterns in critically ill patients including abnormal circadian rhythm, high arousal and awakening index, reduced Slow Wave Sleep, and Rapid Eye Movement sleep. The purpose of this study is to summarise different aspects of sleep-awake disturbances, causes and handling methods in critically ill patients by reviewing the underlying literature. There are no studies of level 1 evidence proving the positive impact of the tested interventions on the critically ill patients' sleep pattern. Thus, disturbed sleep in critically ill patients with all the severe consequences remains an unresolved problem and needs further investigation.

Sleep deprivation in critical illness: its role in physical and psychological recovery

Critically ill patients frequently experience poor sleep, characterized by frequent disruptions, loss of circadian rhythms, and a paucity of time spent in restorative sleep stages. Factors that are associated with sleep disruption in the intensive care unit (ICU) include patient-ventilator dysynchrony, medications, patient care interactions, and environmental noise and light. As the field of critical care increasingly focuses on patients' physical and psychological outcomes following critical illness, understanding the potential contribution of ICU-related sleep disruption on patient recovery is an important area of investigation. This review article summarizes the literature regarding sleep architecture and measurement in the critically ill, causes of ICU sleep fragmentation, and potential implications of ICU-related sleep disruption on patients' recovery from critical illness. With this background information, strategies to optimize sleep in the ICU are also discussed.