Is There an Association between Sleeping Patterns and Other Environmental Factors with Obesity and Blood Pressure in an Urban African Population?

Sex-specific associations between self-reported sleep characteristics and 10-year cardiovascular disease risk in men and women of African descent living in a low socioeconomic status environment

Background

Risk factors for cardiovascular disease (CVD) and sleep health are well-known to be sex- and race-specific. To build on the established relationship between sleep duration and CVD risk, this cross-sectional study aimed to describe sex-specific associations between CVD risk and other sleep characteristics (sleep quality, sleep timing and sleep onset latency) in low-income adults of African descent.

Methods

Self-reported sleep (Pittsburgh Sleep Quality Index [PSQI], Epworth Sleepiness Scale [ESS], Insomnia Severity Index [ISI]), demographic and lifestyle data were collected in 412 adults (56 % women, 35.0 ± 7.6y, 40 % employed) living in an informal settlement in South Africa. CVD risk was determined using the BMI-modified Framingham 10-year CVD risk formula.

Results

Logistic regression analyses, adjusted for employment, alcohol use and physical activity, indicated that men reporting poor sleep quality (OR: 1.95[95 %CI: 1.07-3.51], p=0.025) and earlier bedtimes (0.54[0.39-0.74], p<0.001) were more likely to belong to a higher 10-year CVD risk score quintile. Women reporting earlier bedtimes (0.72[0.55-0.95], p=0.020) and wake-up times (0.30[0.13-0.73], p=0.007), longer sleep-onset latency (1.47[1.43-1.88], p=0.003), shorter total sleep times (0.84[0.72-0.98], p=0.029), higher PSQI global scores (1.93[1.29-2.90], p=0.001) and more moderate to severe symptoms of insomnia (ISI≥15)(3.24[1.04-10.04], p=0.016) were more likely to belong to higher 10-year CVD risk score quintile.

Conclusion

In addition to sleep duration, we found that sleep quality, sleep timing and sleep onset latency are additional risk factors for CVD in adults of African descent. Sex-specific differences in the sleep-CVD-risk relationship observed suggests that future studies and recommendations about sleep health in relation to CVD should take sex into account.

Associations between fears related to safety during sleep and self-reported sleep in men and women living in a low-socioeconomic status setting

South Africans living in low socioeconomic areas have self-reported unusually long sleep durations (approximately 9-10 h). One hypothesis is that these long durations may be a compensatory response to poor sleep quality as a result of stressful environments. This study aimed to investigate whether fear of not being safe during sleep is associated with markers of sleep quality or duration in men and women. South Africans (n = 411, 25-50 y, 57% women) of African-origin living in an urban township, characterised by high crime and poverty rates, participated in this study. Participants are part of a larger longitudinal cohort study: Modelling the Epidemiologic Transition Study (METS)-Microbiome. Customised questions were used to assess the presence or absence of fears related to feeling safe during sleep, and the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index were used to assess daytime sleepiness, sleep quality and insomnia symptom severity respectively. Adjusted logistic regression models indicated that participants who reported fears related to safety during sleep were more likely to report poor sleep quality (PSQI > 5) compared to participants not reporting such fears and that this relationship was stronger among men than women. This is one of the first studies outside American or European populations to suggest that poor quality sleep is associated with fear of personal safety in low-SES South African adults.

Objectively-measured sleep patterns and cardiometabolic health in a rural South African setting: a cross sectional analysis

Background

To investigate the relationship between objectively-measured, free-living sleep patterns, and cardiometabolic health, in a rural South African health and demographic surveillance site.

Methods

Wrist-mounted actigraphy data was collected over nine days from 167 adults (≥ 40 years). Sleep patterns were constructed from tertiles of sleep quantity and quality parameters (TST: total sleep time, AC: activity counts during sleep) from valid minute-by-minute data. The reference category was Moderate TST/Low-to-Moderate AC. Self-reported data included behavioural, health and socio-demographic variables. Biological data included anthropometry, resting blood pressure and fasting blood glucose, insulin and lipids. Binary and ordinal logistic regression models were constructed to determine the association between TST and AC, the factors associated with sleeping patterns, and the association between sleeping patterns and Insulin resistance (HOMA-IR) and Metabolic Syndrome (MetS). HOMA-IR and MetS were also examined across sleep patterns using analysis of variance models.

Results

A total of 139 adults (71.2% female) had a complete dataset. In unadjusted analyses, females had poorer sleep quality, were more physically active, and displayed poorer cardiometabolc health and greater adiposity than males (p ≤ 0.017). There were no sex differences in TST or sleep pattern distribution (p ≤ 0.901). Not being classified as Low TST/High AC or exposed to ≥ 1 bout of Low TST/High AC sleep was associated with lower physical activity, longer sleep duration, better sleep quality and lower IR (p ≤ 0.0452). In multivariate analyses, there was no association between TST and AC (p = 0.921), while increasing age and people-to-bedroom density, and lower physical activity where significantly associated with increasing TST (p ≤ 0.027). Participants classified as Low TST/High AC had significantly higher HOMA-IR, but not MetS, compared with Moderate TST/Low AC (p = 0.021). Being exposed to ≥ 1 bout of Low TST/High AC sleep was significantly associated with hypertension (OR = 2.31, 95%CI: 1.00, 5.34), but not for HOMA-IR or MetS (p ≥ 0.227).

Conclusions

Long sleep was not associated with increased sleep fragmentation. Short, fragmented sleep was associated with insulin resistance. Exposure to at least one bout of short, fragmented sleep increased the likelihood of hypertension. Further studies are required to identify the factors associated with short, fragmented sleep in this setting.

The association of actigraphy-assessed sleep duration with sleep blood pressure, nocturnal hypertension, and nondipping blood pressure: the coronary artery risk development in young adults (CARDIA) study

OBJECTIVE

Nocturnal hypertension and nondipping systolic blood pressure (SBP) are associated with increased cardiovascular disease (CVD) risk. Short and long sleep duration (SSD and LSD) are also associated with increased CVD risk and may be risk factors for nocturnal hypertension and nondipping SBP. We examined the association between SSD and LSD with sleep BP, nocturnal hypertension, and nondipping SBP among 647 white and African American Coronary Artery Risk Development in Young Adults (CARDIA) study participants who completed 24-h ambulatory BP monitoring, wrist actigraphy, and sleep diaries in 2015-2016.

METHODS

The times when participants were asleep and awake were determined from actigraphy complemented by sleep diaries. Nocturnal hypertension was defined as sleep BP ≥120/70 mmHg and nondipping SBP as mean sleep-to-awake SBP ratio >0.90. Sleep duration was categorized as SSD (<6 h), normal sleep duration (NSD: 6-8.9 h), and LSD (≥9 h).

RESULTS

The prevalence of SSD and LSD were 13.9 and 21.1%, respectively. Compared to participants with NSD, participants with LSD had higher mean sleep SBP (2.1 mmHg, 95% confidence interval [CI] 0.2, 4.1 mmHg) and diastolic BP (1.7 mmHg, 95% CI 0.5, 3.0 mmHg). Participants with LSD had a higher prevalence of nocturnal hypertension (prevalence ratio [PR]: 1.26, 95% CI 1.03-1.54) and nondipping SBP (PR 1.33, 95% CI 1.03-1.72) compared to participants with NSD. There was no evidence of an association between SSD and sleep SBP or DBP, nocturnal hypertension, or nondipping SBP.

CONCLUSIONS

These findings suggest that LSD may be associated with nocturnal hypertension and nondipping SBP.

Improved Sleep Quality and Depressive Symptoms With Exercise Training in Obese Women From a Low Socioeconomic Community: A Randomized Controlled Trial

BACKGROUND

Improving sleep quality and reducing depressive symptoms may be target mechanisms for intervention-based research aimed at reducing cardiometabolic risk in low-income communities. This study assessed the effects of exercise training on depressive symptoms and sleep in obese women for a low socioeconomic community. The secondary aim explored associations between changes in depressive symptoms and sleep with changes in cardiorespiratory fitness and cardiometabolic risk factors.

METHODS

Participants were randomized into exercise (n = 20) or control (n = 15) groups. The exercise group completed 12 weeks of combined resistance and aerobic training (40-60 min, 4 d/wk), and the control group maintained habitual diet and activity. Preintervention and postintervention testing included questionnaires on symptoms of depression, psychological distress, and sleep quality. Sedentary time, peak oxygen consumption, body mass index, and insulin sensitivity were measured objectively. Sleep duration (accelerometry) was assessed at preintervention and weeks 4, 8, and 12.

RESULTS

Exercise training reduced depressive symptoms (P = .002) and improved sleep quality (P < .001) and sleep efficiency (P = .005). Reduced depressive symptoms were associated with improved peak oxygen consumption (rho = -.600, P < .001), and improved sleep quality correlated with reduced sedentary time (rho = .415, P = .018).

CONCLUSION

These results highlight the potential for community-based exercise interventions to simultaneously address multiple comorbidities in a low-income setting.

Descriptive epidemiology of objectively-measured, free-living sleep parameters in a rural African setting

OBJECTIVES

To investigate the descriptive nature of objectively-measured, free-living sleep quantity and quality, and the relationship to adiposity, in a rural African setting in 145 adults (≥ 40 years, female: n = 104, male: n = 41). Wrist-mounted, triaxial accelerometry data was collected over 9 days. Measures of sleep quantity and quality, and physical activity were extracted from valid minute-by-minute data. Adiposity indices were body-mass-index, waist circumference and conicity index. Self-reported data included behavioural, health and socio-demographic variables. Community consultation followed the quantitative data analyses, for validation and interpretation of findings.

RESULTS

Females had more nocturnal sleep than males (7.2 vs. 6.8 h/night, p = 0.0464) while males recorded more diurnal sleep time (p = 0.0290). Wake after sleep onset and number of awakenings were higher in females, and sleep efficiency was higher in males (p ≤ 0.0225). Sleep indices were generally similar between weekdays and weekends, except for sleep fragmentation index (p = 0.0458). Sleep quantity, but not sleep quality was independently and inversely associated with adiposity (p = 0.0453). Physical activity and morbidity measures were significantly and consistently associated with sleep and adiposity measures (p < 0.0458). The preliminary qualitative data suggests that future studies should include more detailed data around contextual issues of sleep (social, cultural, economic, environment).

Associations between self-reported sleep duration and cardiometabolic risk factors in young African-origin adults from the five-country modeling the epidemiologic transition study (METS)

OBJECTIVES

To investigate associations between self-reported sleep duration and cardiometabolic (CM) risk factors in African-origin adults residing in five countries spanning the epidemiologic transition.

DESIGN

Cross-sectional.

SETTING AND PARTICIPANTS

Ghanaian (n = 491), South African (n = 503), Jamaican (n = 508), Seychellois (n = 501) and American (n = 480) men and women.

MEASUREMENTS

Self-reported sleep duration was obtained using questionnaires. Sex- and site-stratified logistic regression analyses investigated relationships between sleep duration, individual CM risk factors and a binary CM risk variable (presence of ≥3 CM risk factors), adjusting for age, physical activity and education.

RESULTS

Sleep duration distributions varied by cohort: 44.5%, 41.4%, 35.9%, 16.8% and 2.5% of American, Jamaican, Seychellois, Ghanaian and South African men reported <7 h sleep per night respectively (p < 0.001). Similarly, 42.6%, 28.6%, 25.2%, 12.8% and 1.5% of American, Jamaican, Seychellois, Ghanaian and South African women reported <7 h sleep respectively (p < 0.001). American men reporting ≤6 h sleep were more likely to be in the elevated CM risk group (OR: 2.52, 95%CI: 1.02, 6.22, p = 0.045) and to have a high waist circumference (OR: 2.44, 95%CI: 1.07, 5.57, p = 0.034) compared to those reporting 8 h sleep. Jamaican women reporting ≤6 h sleep (OR: 2.53, 95%CI: 1.19, 5.36, p = 0.016) and American women reporting 7 h sleep (OR: 2.71, 95%CI: 1.17, 6.26, p = 0.002) were more likely to be obese than those reporting 8 h sleep.

CONCLUSIONS

Associations between short sleep and CM risk factors were only evident in the American men and women and Jamaican women. Future interventions to address CM risk and sleep health may need to be country-specific when targeting high-risk populations.

Sleep Duration and Blood Pressure: Recent Advances and Future Directions

PURPOSE OF REVIEW

This review discusses the recent literature on subjectively and objectively assessed sleep duration in relation to hypertension risk and out-of-clinic blood pressure (BP) measures and highlights critical areas for future research.

RECENT FINDINGS

Sleep duration, particularly short sleep, may influence BP through disturbed autonomic balance, hormonal imbalances, increased adiposity and metabolic dysfunction, and disrupted circadian rhythms. Observational studies indicate that short and long sleep are associated with hypertension risk, reduced nocturnal dipping, and elevated morning BP, but evidence is stronger for short sleep. Experimental sleep restriction increases BP, while sleep extension may lower BP in prehypertensive individuals. Women and racial/ethnic minorities are more prone to the detrimental effects of short sleep on BP. Additional studies are warranted to clarify the association of objectively assessed sleep with BP level and diurnal pattern and to determine the sex- and race-specific effects of sleep restriction and extension on BP.

Associations between sleep parameters, non-communicable diseases, HIV status and medications in older, rural South Africans

As part of the Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa (HAALSI), we investigated sleep habits and their interactions with HIV or non-communicable diseases (NCDs) in 5059 participants (median age: 61, interquartile range: 52—71, 54% females). Self-reported sleep duration was 8.2 ± 1.6h, and bed and rise times were 20:48 ± 1:15 and 05:31 ± 1:05 respectively. Ratings of insufficient sleep were associated with older age, lack of formal education, unemployment, and obesity (p < 0.05). Ratings of restless sleep were associated with being older, female, having more education, being unemployed, and single. Hypertension was associated with shorter self-reported sleep duration, poor sleep quality, restless sleep, and periods of stopping breathing during the night (p < 0.05). HIV positive individuals not on antiretroviral treatment (ART) reported more nocturnal awakenings than those on ART (p = 0.029) and HIV negative individuals (p = 0.024), suggesting a negative net effect of untreated infection, but not of ART, on sleep quality. In this cohort, shorter, poor-quality sleep was associated with hypertension, but average self-reported sleep duration was longer than reported in other regions globally. It remains to be determined whether this is particular to this cohort, South Africa in general, or low- to middle-income countries undergoing transition.

Associations between long self-reported sleep, obesity and insulin resistance in a cohort of premenopausal Black and White South African women

OBJECTIVES

South African women have disproportionately high levels of overweight and obesity, and ethnic differences in obesity and insulin resistance have been observed. We investigated associations between self-reported sleep duration, obesity and insulin resistance in Black and White South African women.

DESIGN

Cross-sectional.

PARTICIPANTS

Black normal-weight (n = 122), Black obese (n = 133), White normal-weight (n = 87) and White obese (n = 63) urban South African women, aged 18 to 45y.

MEASUREMENTS

Participants completed questionnaires capturing self-reported sleep duration, demographic, socioeconomic, medical history and lifestyle information. Body composition and fasting blood glucose and insulin concentrations were measured.

RESULTS

The Black women reported longer sleep than the White women (median: 8 h, interquartile range: 8-10 h v 7(7-8) respectively, P < .001). Adjusted models indicated that women sleeping <7 h sleep were less likely to be obese (P = .035) or insulin resistant (P = .032), while those sleeping >9 h were more likely to be insulin resistant (P = .014) than those sleeping 7 to 9 h. Shorter self-reported sleep was associated with less insulin resistance (<7 h v 7-9 h: P = .018) and longer sleep with more insulin resistance (>9 h v 7-9 h: P = .047) in the Black but not White women.

CONCLUSIONS

Future research that objectively measures sleep duration is needed to confirm these observations and investigate potential factors contributing to the relationship between sleep and risk for non-communicable diseases in different ethnic groups.

Determinants of body mass index by gender in the Dikgale Health and Demographic Surveillance System site, South Africa

BACKGROUND

The study was conducted in the Dikgale Health and Demographic Surveillance System (DHDSS) site where we have observed increasing obesity levels, particularly in women, despite evidence of high physical activity (PA) and a relatively low daily energy intake.

OBJECTIVE

This study aimed to assess the socio-demographic, behavioural and biological determinants of body mass index (BMI) in adult residents permanently residing in the DHDSS.

METHODS

A cross-sectional study was conducted in which socio-demographic, behavioural and biological characteristics from 1143 participants (aged 40-60 years) were collected using a paper questionnaire and standard anthropometric measures. Human immunodeficiency virus (HIV) testing was performed on all participants except those who indicated that they had tested positive. Chi-square and Mann-Whitney tests were used to analyze categorical and continuous variables, respectively, while hierarchical multivariate regression was used to analyze predictors of BMI.

RESULTS

The median age of women and men was 51 (46-56) and 50 (45-55) years, respectively. The prevalence of overweight-obesity was 76% in women and 21% in men. A significant negative association of BMI with HIV and smoking and a significant positive association with socio-economic status (SES) was observed in both sexes. In women, BMI was negatively associated with sleep duration (p = 0.015) and age (p = 0.012), but positively associated with sugar-sweetened beverages (SSBs) (p = 0.08). In men, BMI was negatively associated with alcohol use (p = 0.016) and positively associated with being married (p < 0.001). PA was not associated with BMI in either sexes. Full models explained 9.2% and 20% of the variance in BMI in women and men, respectively.

CONCLUSION

BMI in DHDSS adults is not associated with physical inactivity but is associated wealth, marital status, sleep, smoking, alcohol use, and HIV status. Future studies should explore the contribution of nutrition, stunting, psycho-social and genetic factors to overweight and obesity in DHDSS.

Review: Metabolic Syndrome in Black South African Women

The prevalence of metabolic syndrome is increasing in African populations, and is particularly high in Black South African women (42%) vs women in the United Kingdom (23%) and the United States of America (36%). This population group is also known to have the highest prevalence of obesity in the sub-Saharan African region (42%), and consequently, a high risk of non-communicable diseases. In this article, we discuss factors (abdominal subcutaneous fat, visceral fat, lean mass, adiponectin, leptin, vitamin D, smoking and menopausal status) that have been investigated for their possible association with metabolic syndrome in African women, and discuss some recommendations for management of the syndrome. In particular, the infrastructural development of HIV/AIDS clinics in South Africa provides an ideal integrated platform to cater to the treatment needs of patients with multiple chronic morbidities.