Sleep and physiological systems: a functional perspective

The effect of electro-magnetic-energy-regulation therapy on subjective sleep among elite players in Norwegian women's football

The current study investigated if Bio-Electro-Magnetic-Energy-Regulation (BEMER) therapy is affecting subjective sleep among a sample of 21 elite female football players in a Norwegian top series club. Subjective sleep was measured each day over a period of 273 consecutive days by using a smartphone application, PM Reporter Pro, which scheduled push messages to remind the participants to report sleep every morning. The study was conducted as a quasi-experimental design, with a control period before the introduction of BEMER therapy that lasted for 3 months, followed by an intervention period where BEMER therapy was used that lasted for 5 months. The collected data from the players in the control period served as their control compared to the data collected from the players in the intervention period. Analyses of variance (ANOVA) with False Discovery Rate adjusted p-values show that subjective sleep duration and subjective sleep quality are significantly reduced on game nights, both in the control period and in the experiment period. The results also show that subjective sleep duration and subjective sleep quality significantly increase in the experiment period compared to the control period. The findings indicate that BEMER therapy might serve as a tool to improve sleep.

Sleep in the wild: the importance of individual effects and environmental conditions on sleep behaviour in wild boar

Sleep serves vital physiological functions, yet how sleep in wild animals is influenced by environmental conditions is poorly understood. Here we use high-resolution biologgers to investigate sleep in wild animals over ecologically relevant time scales and quantify variability between individuals under changing conditions. We developed a robust classification for accelerometer data and measured multiple dimensions of sleep in the wild boar (Sus scrofa) over an annual cycle. In support of the hypothesis that environmental conditions determine thermoregulatory challenges, which regulate sleep, we show that sleep quantity, efficiency and quality are reduced on warmer days, sleep is less fragmented in longer and more humid days, while greater snow cover and rainfall promote sleep quality. Importantly, this longest and most detailed analysis of sleep in wild animals to date reveals large inter- and intra-individual variation. Specifically, short-sleepers sleep up to 46% less than long-sleepers but do not compensate for their short sleep through greater plasticity or quality, suggesting they may pay higher costs of sleep deprivation. Given the major role of sleep in health, our results suggest that global warming and the associated increase in extreme climatic events are likely to negatively impact sleep, and consequently health, in wildlife, particularly in nocturnal animals.

Sleep duration during the COVID-19 pandemic in Bangladesh: A GIS-based large sample survey study

Although several studies have been conducted in Bangladesh regarding sleep problems during the COVID-19 pandemic, none have utilized a large nationwide sample or presented their findings based on nationwide geographical distribution. Therefore, the aim of the present study was to explore the total sleep duration, night-time sleep, and daily naptime and their associated factors as well as geographic information system (GIS) distribution. A cross-sectional survey was carried out among 9730 people in April 2020, including questions relating to socio-demographic variables, behavioral and health factors, lockdown, depression, suicidal ideation, night sleep duration, and naptime duration. Descriptive and inferential statistics, both linear and multivariate regression, and spatial distribution were performed using Microsoft Excel, SPSS, Stata, and ArcGIS software. The results indicated that 64.7% reported sleeping 7-9 h a night, while 29.6% slept less than 7 h nightly, and 5.7% slept more than 9 h nightly. 43.7% reported 30-60 min of daily nap duration, whereas 20.9% napped for more than 1 h daily. Significant predictors of total daily sleep duration were being aged 18-25 years, being unemployed, being married, self-isolating 4 days or more, economic hardship, and depression. For nap duration, being aged 18-25 years, retired, a smoker, and a social media user were at relatively higher risk. The GIS distribution showed that regional division areas with high COVID-19 exposure had higher rates of non-normal sleep duration. Sleep duration showed a regional heterogeneity across the regional divisions of the country that exhibited significant associations with a multitude of socioeconomic and health factors.

Association of Glaucoma with Poor Quality of Sleep in an Ethiopian Glaucoma Population – A Comparative Cross-Sectional Study

Background

Glaucoma is a group of ocular disorders characterized by progressive optic nerve damage resulting in irreversible visual field defects. Poor quality of sleep in glaucoma patients could be explained by the reduction of the light input to the circadian system as a result of damage to photosensitive retinal ganglion cells in the retina. Information is limited on the association of poor quality of sleep with glaucoma in general and the Ethiopian glaucoma population in particular.

Objective

The study aimed to explore the association between poor quality of sleep and glaucoma at a Tertiary Eye Care Center in Ethiopia.

Methods

An institutional-based comparative cross-sectional study was conducted among 200 glaucoma and 201 non-glaucoma participants recruited by systematic random sampling. Each group was administered with a Pittsburgh Sleep Quality Index (PSQI) questionnaire. Stata-14 was employed for data analysis; an independent t-test was used to show the statistical difference in the global mean PSQI score for the two groups. A binary logistic regression model was applied to identify factors associated with poor quality of sleep. Statistical significance was declared at a 95% confidence interval and a p-value of <0.05.

Results

The prevalence of poor quality of sleep was 82.5% among the glaucoma population, which statistically differed (p<0.001) from the non-glaucomatous population (55.7%). Poor quality of sleep in glaucoma was associated with older age (adjusted odds ratio (AOR)=4.4, 95% confidence interval (CI): 1.5–5.4), depression (AOR=2.9, 95% CI: 1.1–7.3), visual impairment (AOR=3.9, 95% CI: 1.3–12.3) and severe glaucoma (AOR=2.5, 95% CI: 1.1–5.9).

Conclusion and Recommendation

Poor quality of sleep was significantly higher in the glaucoma population compared to their non-glaucoma control. It was associated with older age, depression, visual impairment and advanced glaucoma. Incorporating psychiatric counseling into the existing glaucoma follow-up was recommended.

Poor Sleep in Community-Dwelling Polysubstance Users: Association With Khat Dependence, Metacognition, and Socio-Demographic Factors

Purpose

Poor sleep and cognitive deficits are often associated with increased drug use. However, no study has addressed the relationship between poor sleep, substance dependence, and metacognitive deficit in polysubstance users.

Methods

This was a cross-sectional study with a simple random sampling involving community-dwelling polysubstance users (n = 326, age = 18-43 years) in Mizan, Ethiopia. Participants completed a brief sleep questionnaire, severity of dependence on khat (SDS-Khat), a brief meta-cognition questionnaire, and a socio-demographic survey.

Results

Majority (56.4%) of the polysubstance users had sleep disturbance. Chronic health conditions [adjusted odds ratio (AOR) = 2.52, 95% confidence interval (CI) 1.31-4.85], chronic conditions in the family (AOR = 2.69, 95% CI 1.40-5.20), illiterate-primary level of educational status (AOR = 2.40, 95% CI 1.30-4.04), higher SDS-Khat score (AOR = 1.39, 95% CI 1.13-1.72), and lower meta-cognition score (AOR = 0.90, 95% CI 0.84-0.97) predicted poor sleep in the polysubstance users. Moreover, low metacognition score and high SDS score also predicted additional sleep disturbances like chronic sleep insufficiency, lethargy and restlessness after nighttime sleep, socio-occupational dysfunctions, and daytime disturbances in polysubstance users.

Conclusion

Poor sleep, severe khat dependence, and metacognitive deficits are common in community polysubstance users. Moreover, poor sleep is associated with higher khat dependence, lower metacognitive ability, lower educational status, and the presence of chronic conditions in polysubstance users or their families.

Structural validity of the Insomnia Severity Index: A systematic review and meta-analysis

The factor structure of the Insomnia Severity Index (ISI) is discussed, with examples being drawn from about 13 disparate reported models. A systematic appraisal of procedural details of studies investigating the dimensionality of the ISI was performed. The databases CINAHL, Cochrane Library, Embase, Medline, and PsycINFO were searched thoroughly, and all articles in English, published, and/or available online as of 14th March 2019, were included. Meta-analyses of Cronbach's alpha and structural validity measures were performed. Several inadequacies or omissions were found in analyses using the three groups of measures. Fifteen out of 20 studies did not employ either EFA or CFA, 10 studies did not report CFA, while five did not report EFA. The most common omissions related to multivariate normality, final model selection based on consideration of fit indices, parsimony, and failure to consider the theoretical construct in the final model selection. Meta-analysis showed that CFA outcome is more robust compared to EFA, two-factor solution is the vigorous presentation of dimensionality compared to a three-factor solution, and ISI has a high pooled Cronbach's alpha. Further validation of the disparate models of the ISI is needed with more comprehensive reporting guidelines, such as the one suggested in the present review.

Reciprocal Associations Between Sleep, Mental Strain, and Training Load in Junior Endurance Athletes and the Role of Poor Subjective Sleep Quality

The importance of adequate sleep for athletic functioning is well established. Still, the literature shows that many athletes report sleep of suboptimal quality or quantity. To date, no research has investigated how bidirectional variations in mental and physiological states influence sleep patterns. The present study, therefore, investigates reciprocal associations between sleep, mental strain, and training load by utilizing a prospective, observational design. In all, 56 junior endurance athletes were followed over 61 consecutive days. Unobtrusive, objective measurements of sleep with novel radar technology were obtained, and subjective daily reports of mental strain and training load were collected. The role of subjective sleep quality was investigated to identify whether the reciprocal associations between sleep, mental strain, and training load depended on being a good versus poor sleeper. Multilevel modeling with Bayesian estimation was used to investigate the relationships. The results show that increases in mental strain are associated with decreased total sleep time (TST, 95% CI = −0.12 to −0.03), light sleep (95% CI = −0.08 to −0.00), and sleep efficiency (95% CI = −0.95 to −0.09). Further, both mental strain and training load are associated with subsequent deceased rapid eye movement (REM, respectively, 95% CI = −0.05 to −0.00 and 95% CI = −0.06 to −0.00) sleep. Increases in TST, light, deep, and REM sleep are all associated with subsequent decreased training load (respectively, 95% CI = −0.09 to −0.03; 95% CI = −0.10 to −0.01; 95% CI = −0.22 to −0.02; 95% CI = −0.18 to −0.03). Finally, among poor sleepers, increases in sleep onset latency are associated with increases in subsequent mental strain (95% CI = 0.09–0.46), and increases in deep sleep are associated with decreases in subsequent training load (95% CI = −67.65 to 11.43). These results offer novel insight into the bidirectional associations between sleep, mental strain, and training load in athletes and demonstrate the detrimental effects of mental strain on sleep, likely caused by mental activation incompatible with sleep. An increased need for recovery, suggested by increased TST and time in different sleep stages, is associated with subsequent self-regulatory reduction of training loads by the athletes. In poor sleepers, increases in deep sleep may suggest an elevated need for physiological recovery.

Prevalence of poor sleep quality in the Ethiopian population: a systematic review and meta-analysis

BACKGROUND

Only a limited amount of data is available from lower-income countries regarding the prevalence of poor quality of sleep. This meta-analysis of the scientific literature was performed to estimate the pooled prevalence of poor sleep quality in the Ethiopian population.

METHODS

The study protocol followed was the Preferred Reporting of Items for Systematic Review and meta-analysis (PRISMA) statement.

RESULTS

The nine studies which met the inclusion criteria provided data based on a total of 9103 participants who were studied at various health and academic institutions. The incidences of self-reported poor sleep quality ranged from 26 to 66.2%. The pooled estimate of poor sleep quality was 53%.There was a high prevalence of reported poor quality of sleep among younger subjects and among those who were studied in community (noninstitutional) settings.

CONCLUSION

The pooled prevalence of poor sleep quality is quite high among Ethiopians.

Insomnia severity index: a psychometric investigation among Saudi nurses

BACKGROUND

Insomnia is the most prevalent sleep disorder, but it is widely untreated and under-diagnosed in Saudi Arabia. Moreover, no tool to screen insomnia has been validated in the Saudi population in general or nurses in particular. This study, therefore, assessed the psychometric validity of the Insomnia Severity Index (ISI) in Saudi nurses.

METHODS

A cross-sectional study with purposive sampling was performed with nurses (n = 134, age = 21-48 years) from Al Majmaah, Saudi Arabia. Both conventional and online survey methods using the ISI, a brief measure of metacognition, and a socio-demographics questionnaire were employed.

RESULTS

No ceiling or floor effects were found in the ISI total score (8.84 ± 5.07) or the factor scores, but the floor effect was found in the item scores. A two-factor model showed the best fit (Pclose .97, comparative fit index [CFI] 1.00, root mean square error of approximation [RMSEA] 0.00, non-significant χ²test, χ²/df 0.904). This model showed favorable configural, metric, scalar, and partial strict invariance across gender groups (CFI > .95, RMSEA < .05, χ²/df < 3, non-significant Δχ², ΔCFI ≤ .01). The internal consistency was adequate (Cronbach's alpha = 0.75, 0.78 for the two factors of the ISI). The lack of correlations between the ISI scores and the scores of the brief measure of the metacognition favored its divergent validity.

CONCLUSION

The ISI showed adequate psychometric validity for screening insomnia among Saudi nurses.

Dimensionality of the Pittsburgh Sleep Quality Index: a systematic review

Background

The Pittsburgh Sleep Quality Index (PSQI) dimensionality is much debated, with the greatest number of reported factor structures. Therefore, this review appraised the methodologies of studies investigating the factor structure of the PSQI.

Material and methods

MEDLINE, PsycInfo, AJOL, BASE, Cochrane Library, Directory of Open Access Journals (Lund University), CINAHL, and Embase were searched systematically to include articles published till 23rd March, 2018. The articles with the objective of factor analysis of the PSQI (20 articles) or with a major section on the same subject (25 articles) were included. There was no limitation about participant characteristics. Descriptive analysis of articles for measures of the suitability of the data for factor analysis, details of the exploratory factor analysis (EFA) and details of the confirmatory factor analysis (CFA) was performed.

Results

The analysis used by the majority did not employ the simplest scheme for interpreting the observed data: the parsimony principle. Other shortcomings included under- or non-reporting of sample adequacy measures (11 out of 45 articles), non-use of EFA (20 out of 45 articles), use of EFA without relevant details, non-use of CFA (11 out of 45 articles), and use of CFA without relevant details. Overall, 31 out of 45 articles did not use either EFA or CFA.

Conclusion

We conclude that the various PSQI factor structures for standard sleep assessment in research and clinical settings may need further validation.

Trial registration

Not applicable because this was a review of existing literature.

Polysomnographic correlates of inflammatory complement components in young healthy males

A growing body of evidence has delineated the predominant role of humoral mediators of inflammation in linking sleep with immunity. Nonetheless, characterization of the relationship between complement components with inflammatory functions and objective sleep measures has not been performed. In this study we investigated the relationships between objective measures of sleep and complement components with inflammatory functions. Thirty-six healthy male university students (age, 23.94±4.23 years; BMI, 23.44±2.67 kg/m(2)) completed the study. An RMS Quest 32 polysomnograph (PSG) was used for sleep recording. Non-fasting blood was collected before subjects went to bed on the second night in the sleep laboratory to estimate complement component 3 (C-3), complement component 4 (C-4), complement factor-H (Factor-H), C1-inhibitor (C1INH), complement factor I (CFI) and other inflammatory mediators, such as IL-6 and sICAM-1. Multiple linear regression analysis was used to assess the association between PSG sleep measures and inflammatory mediators. Higher values of C-3 and lower values of sICAM-1, C1INH, and CFI (adjusted model, R2=0.211, p<0.041) predicted longer sleep duration. Lower C-3 (adjusted model, R2=0.078, p<0.055) predicted higher N1 (%). Higher levels of C1INH and CFI and lower values of C-4 (model adjusted R2=0.269, p<0.008) predicted higher N3 (%). Higher C-3, higher C-4, lower IL-6, lower C1INH and lower CFI (model adjusted R2=0.296, p<0.007) predicted higher REM (%). Poor sleep measures were associated with increased levels of pro-inflammatory complement components and decreased anti-inflammatory complement components.