Association between daytime napping and obesity in Chinese middle-aged and older adults

Rural-urban differences in the association between afternoon napping and depressive symptoms among middle-aged and older adults in China

OBJECTIVE

This study aimed to examine the association between afternoon napping and depressive symptoms among Chinese middle-aged and older adults and to evaluate the rural-urban differences.

METHODS

A total of 11,056 participants, aged≥45, 5646 rural and 5410 urban, were included using data from CFPS. Each participant provided data on afternoon napping through field interviews. CESD8 was used to measure depressive symptoms. Multivariable logistic regressions were used to investigate the association.

RESULTS

2654 (24.01 %) participants had depressive symptoms and 7239 (65.48 %) napped. Nappers were likely to have a lower risk of depressive symptoms (OR = 0.899; 95%CI =0.816-0.991). A significantly lower risk of depressive symptoms was found in the moderate-duration afternoon napping groups (31-60 min/day) compared with non-nappers (OR = 0.816; 95%CI =0.727-0.917). In terms of rural-urban differences, rural participants had a lower risk of depressive symptoms compared with non-nappers (OR = 0.813; 95%CI =0.716-0.926). A significant association was also found between age groups. Participants aged 65-74 years old had a lower risk of depressive symptoms compared with non-nappers (OR = 0.776; 95%CI = 0.627-0.959).

LIMITATIONS

First, the cross-sectional study may limit the ability to infer causality. Second, only those who responded to the questionnaire were included; selection bias was unavoidable. Finally, answers were retrospective self-reported, which may cause recall bias and social desirability bias.

CONCLUSIONS

Afternoon napping was associated with a lower risk of depressive symptoms among Chinese middle-aged and older adults. The associations varied between rural-urban and age groups. We recommend taking a moderate-duration afternoon napping every day to prevent the risk of potential depression.

Day napping and metabolic-associated fatty liver disease: A systematic review and meta-analysis of observational studies

BACKGROUND

Napping inevitably affects human health, and the association between napping and metabolism-related diseases is being more seriously considered. However, the conclusions of studies on the relationship between napping and fatty liver disease (NAFLD)/metabolic-associated fatty liver disease (MAFLD) remain controversial.

METHODS

We performed a systematical search to identify eligible studies up to July 31, 2024. The fixed effects model was used to calculate the pooled odds ratio (OR). Subgroup were performed. Sensitivity analyses and meta-regression analysis were carried to explore the heterogeneity. Publication bias was assessed by funnel plot and Egger's test.

RESULTS

48,248 participants from 13 studies were included in this meta-analysis. The pooled analysis found napping to have an association between the incidence of NAFLD/MAFLD (OR, 1.13; 95% confidence interval (CI), 1.08-1.19; P < .001). The robustness of this study was confirmed using a sensitivity analysis. No apparent heterogeneity or publication bias was observed. Further meta-analysis revealed that short nap duration did not greatly affect the incidence of the disease (OR, 1.01; 95% CI, 0.91-1.12; P = .80). However, long nap duration was significantly linked to high risk of the disease (OR, 1.21; 95% CI, 1.02-1.44; P = .03).

CONCLUSION

Patients with NAFLD/MAFLD may had higher prevalence of napping habit. Future research is warranted to conduct a dose-response analysis, measure the effects of confounding factors, and explore the causal relationships between NAFLD/MAFLD. The research protocol was registered and approved in PROSPERO (registration no: CRD42023439507).

Results of two cross-sectional database analyses regarding nap-induced modulations of tinnitus

The influence of naps on tinnitus was systematically assessed by exploring the frequency, clinical and demographic characteristics of this phenomenon. 9,724 data from two different tinnitus databases (Tinnitus Hub: n = 6115; Tinnitus Research Initiative (TRI): n = 3627) were included. After separate analysis of the databases, these results were then compared with each other. In the Tinnitus Hub survey database, a total of 31.1% reported an influence on tinnitus by taking a nap (26.9% in the TRI database), with much more frequent worsening after a nap than improvement (23.0% a little or a lot worse; TRI: 17.7% worse; 8.1% a little or a lot better; TRI: 9.2% better). The influence of napping on tinnitus was associated in both databases with other clinical features, such as the dependence of tinnitus on night quality, stress and somatosensory maneuvers. The present study confirms the clinical observation that more tinnitus sufferers report worsening after a nap than tinnitus sufferers reporting an improvement. It was consistently shown that tinnitus sufferers reporting nap-induced modulation of tinnitus also report more frequently an influence of night sleep on their tinnitus. Further clinical and polysomnographic research is warranted to better understand the interaction between sleep and tinnitus.

Association of insomnia and daytime napping with metabolic syndrome and its components in a Korean population: an analysis of data from the Korean Genome and Epidemiology Study

OBJECTIVES

We investigated the association between metabolic syndrome (MetS) and the coexistence of insomnia and daytime napping, because limited data have been reported regarding this association.

METHODS

The study population was 8,440 participants aged 40-65 years, who were from the Korean Genome and Epidemiology Study. Self-reported information on insomnia symptoms and nap duration was used to define exposure variables. Data on waist circumference (WC), blood pressure (BP), and fasting blood glucose (FBG), triglyceride (TG), and high-density lipoprotein cholesterol levels in blood were used to define MetS. Multivariate logistic regression analysis was performed to obtain odds ratio (OR) and 95% confidence interval (CI).

RESULTS

In multivariate logistic regression analysis, the coexistence of insomnia and napping was not significantly associated with MetS. However, the insomnia and non-napping group showed higher ORs of high TG (OR, 1.19; 95% CI, 1.02 to 1.39) and high BP (OR, 1.28; 95% CI, 1.10 to 1.49) than the non-insomnia and non-napping group. The combination of non-insomnia and napping and that of insomnia and napping showed higher ORs of high TG (OR, 1.13; 95% CI, 1.00 to 1.29) and high FBG (OR, 1.59; 95% CI, 1.14 to 2.21), respectively. In analyses of insomnia symptoms, only the combination of difficulty in maintaining sleep (DMS) and non-napping showed a higher OR for MetS (OR, 1.25; 95% CI, 1.03 to 1.52) than the non-DMS and non-napping group.

CONCLUSIONS

Individuals with insomnia, particularly those who do not take naps, were disproportionately likely to have MetS components, especially TG or BP. Information on these variables may help predict individuals' vulnerability to specific MetS components.

Sleep-Body Composition Relationship: Roles of Sleep Behaviors in General and Abdominal Obesity in Chinese Adolescents Aged 17-22 Years

This study aimed to investigate the association between sleep behaviors and body composition, which was measured by bioelectrical impedance analysis (BIA) among Chinese adolescents. Overall, 444 students (65.3% females, 19.12 ± 1.177 years) completed questionnaires describing sleep characteristics. Sleep characteristics were derived from subjective means. Body composition was obtained from BIA by InBody 720 (Biospace Co. Ltd., Seoul, Republic of Korea). Regression models tested relationships between sleep and body composition after adjustment for covariates. Students with weekday nap duration (>30 min/d) exerted higher waist-height ratio (WHtR) (B = 0.013, FDR-corrected p = 0.080). Average sleep duration (≤7 h/d) was linked to more WHtR (B = 0.016, FDR-corrected p = 0.080). People with high social jetlag showed gained visceral fat area (B = 7.475), WHtR (B = 0.015), waist to hip ratio (B = 0.012), fat mass index (B = 0.663) and body fat percentage (B = 1.703) (all FDR-corrected p < 0.1). Individuals with screen time before sleep (>0.5 h) exhibited higher visceral fat area (B = 7.934, FDR-corrected p = 0.064), WHtR (B = 0.017, FDR-corrected p = 0.080), waist to hip ratio (B = 0.016, FDR-corrected p = 0.090), fat mass index (B = 0.902, FDR-corrected p = 0.069) and body fat percentage (B = 2.892, FDR-corrected p = 0.018). We found poor sleep characteristics were closely related to general and abdominal obesity.

Associations of multiple sleep dimensions with overall and abdominal obesity among children and adolescents: a population-based cross-sectional study

BACKGROUND

The relationship of insufficient sleep with the increased risk of obesity has been reported, but less is known about other sleep dimensions in the sleep-obesity associations.

OBJECTIVES

To assess the associations of multiple sleep dimensions with overall and abdominal obesity among Chinese students.

METHODS

This was a cross-sectional study involving 10,686 Han students aged 9-18 from Chinese National Survey on Students' Constitution and Health (CNSSCH). We collected sex, age, regions, parental educational levels, physical activity duration and sleep-related information by questionnaire survey, and also conducted anthropometric measurements including height, weight and waist circumference (WC). Unadjusted and adjusted binary logistic regression models were used to estimate the associations of sleep-related dimensions with obesity-related indicators.

RESULTS

Short sleep duration was associated with higher body mass index (BMI), larger WC and higher waist-to-height ratio (WHtR) in 9-12 and 16-18 age groups, whereas prolonged sleep duration on weekday was associated with higher BMI in 13-15 age group. Non-habitual midday napping and midday napping ≤0.5 h/d (vs 0.5 to 1 h/d) increased the risk of higher BMI in 13-15 age group, and the former was also associated with larger WC in 9-12 age group. Late bedtime was associated with larger WC and higher WHtR in 9-12 age group and with higher BMI and WHtR in 13-15 age group. Students aged 9-12 with social jet lag ≥2 h were found to have greater BMI after adjustment (Odds Ratio: 1.421; 95% confidence interval: 1.066-1.894).

CONCLUSIONS

Short or overlong sleep duration, late bedtime and great social jet lag were associated with higher prevalence of overall or abdominal obesity, while moderate midday napping can effectively decrease the risk. Those findings may assist in developing preventive strategies to combat obesity epidemic.

The independent and combined effects of dietary and sleep patterns on the risk of metabolic dysfunction-associated fatty liver disease: a population-based cohort study

Background & aims: accumulating evidence shows that various sleep behaviors are related to metabolic dysfunction-associated fatty liver disease (MAFLD), and that diet plays an important role in both preventing and treating this condition. However, the overall effect of a healthy sleep pattern and its joint effect with diet on the risk of MAFLD remain unclear. The aim of this study is to explore the independent and combined effects of dietary and sleep patterns on the MAFLD risk. Methods: this population-based prospective cohort study was conducted in China with a sample size of 13 687 participants. MAFLD was diagnosed through abdominal ultrasound and international expert consensus. Five healthy sleep behaviors were identified to create a healthy sleep pattern, while factor analysis was used to determine dietary patterns. Cox proportional hazards regression was utilized to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Results: during a total of 49 912 person-years of follow-up, 2977 new cases of MAFLD were identified. The adjusted HRs (95% CIs) of MAFLD in relation to the healthy sleep pattern score were 0.87 (0.78-0.97), 0.83 (0.75-0.92), and 0.77 (0.68-0.87) for scores of 3, 4, and 5, respectively, compared to participants with the lowest score (0-2). A higher intake of animal food (adjusted HR_{4th quartile vs. 1st quartile}, 1.15, 95% CI, 1.03-1.27) and a lower intake of vegetables (adjusted HR_{4th quartile vs. 1st quartile}, 0.88, 95% CI, 0.78-0.99) were associated with a higher risk of MAFLD. Participants who adhered to both healthy dietary and sleep patterns had the lowest MAFLD risk compared to those who followed only one or neither of them. Conclusions: a healthy sleep pattern, especially in combination with a healthy diet, was associated with a lower risk of MAFLD. Future prevention strategies for MAFLD should include consideration of sleep behaviors, in addition to the current recommendations.

The relationship between daytime napping and obesity: a systematic review and meta-analysis

Daytime napping, a habit widely adopted globally, has an unclear association with obesity. In this study, we executed a meta-analysis to explore the relationship between daytime napping and obesity. We conducted a comprehensive search of the PubMed, Embase, Cochrane Library, Scopus, PsycINFO, and Web of Science databases for pertinent articles published up to April 2023. Random-effects models were utilized to calculate odds ratios (ORs) with 95% confidence intervals (CIs), and we assessed the heterogeneity of the included studies using the I² statistic. To explore potential sources of heterogeneity, subgroup analyses were performed. The methodological quality of the studies was evaluated using the Newcastle-Ottawa Scale (NOS), and funnel plots were employed to detect any publication bias. Sensitivity analyses were conducted by sequentially omitting each study. We conducted a meta-analysis of twelve studies that included one each from the UK and Spain, five from the USA, and five from China, totalling 170,134 participants, to probe the association between napping and obesity. The pooled analysis suggested a higher risk of obesity in individuals who nap (OR: 1.22 [1.10-1.35], p < 0.001, I² = 87%) compared to non-nappers. The meta-analysis results revealed variations in the summary ORs for studies conducted in China, Spain, the USA, and the UK. The ORs for China, Spain, the USA, and the UK were 1.05 (95% CI 0.90-1.23), 9.36 (95% CI 4.74-18.45), 1.27 (95% CI 1.10-1.47), and 1.39 (95% CI 1.32-1.47), respectively. A subgroup analysis based on age within the American population disclosed that napping in both adults and children heightened obesity incidence. A subgroup analysis based on nap duration found a significant rise in obesity occurrence when nap duration exceeded one hour, but no clear relationship emerged when nap duration was less than 1 h. In a subgroup analysis based on the definition of obesity, napping did not demonstrate a significant relationship with obesity when diagnostic criteria set obesity at a BMI of 25 or above. However, when the criteria were set at a BMI of 28 or 30 or more, napping significantly increased obesity risk. Our meta-analysis indicates a positive association between daytime napping and the risk of obesity. However, given the limited number of included studies, potential confounding factors might not have been fully addressed. Future well-designed prospective studies are required to further investigate this relationship. Large-scale studies are necessary to confirm our findings and elucidate the underlying mechanisms that drive these associations and causation.

The association between daytime napping and risk of type 2 diabetes is modulated by inflammation and adiposity: Evidence from 435 342 UK-Biobank participants

BACKGROUND

Existing evidence concerning the relationship between daytime napping and type 2 diabetes (T2D) is inconsistent, and whether the effects of napping differ by body fat percentage (BFP) and C-reactive protein (CRP) is unclear. We aimed to investigate the association between daytime napping frequency and T2D risk and whether such an association was modified by BFP and CRP.

METHODS

We included 435 342 participants free of diabetes from the UK Biobank. Participants were categorized as nonnappers, occasional nappers, and frequent nappers based on napping frequency, and BFP/CRP was divided into quartiles. Cox proportional hazards models were used.

RESULTS

During a median follow-up of 9.2 years, 17 592 T2D cases occurred. Higher frequency of daytime napping was significantly associated with an increased risk of T2D. Compared with nonnappers, the adjusted hazard ratios (HRs) for occasional nappers and habitual nappers were 1.28 (95% confidence interval [CI]: 1.24-1.32) and 1.49 (95% CI: 1.41-1.57), respectively. There was a significant additive and multiplicative interaction (relative excess risk due to interaction [RERI] = 0.490, 95% CI 0.307-0.673; p for multiplicative interaction <.001) between napping and BFP, whereby a higher hazard of T2D associated with more frequent napping was greatest among participants in the highest BFP quartile (HR = 4.45, 95% CI: 3.92-5.06). The results for CRP were similar (RERI = 0.266, 95% CI: 0.094-0.439; p for multiplicative interaction <.001).

CONCLUSIONS

Higher daytime napping frequency is associated with an increased T2D risk, and such relationships are modified by BFP and CRP. These findings underscore the importance of adiposity and inflammation control to mitigate diabetes risk.

Predictors of total mortality and their differential association on premature or late mortality in the SUN cohort

Several studies have tried to analyse the association between all-cause mortality and different risk factors, (especially those which are modifiable, such as smoking, diet or exercise), to develop public health preventive strategies. However, a specific analysis of predictors of premature and late mortality is needed to give more precise recommendations. Considering that there are risk factors which exert an influence on some diseases and not on others, we expect that, similarly, they may have a different impact depending on the timing of mortality, separating premature (≤65 years) from late mortality (>65 years). Thus, we prospectively followed-up during a median of 12 years a cohort of 20,272 university graduates comprising an ample range of ages at inception. Time-dependent, covariate-adjusted Cox models were used to estimate adjusted hazard ratios (HR) and their 95 % confidence intervals (CI) for each predictor. The strongest independent predictor of mortality at any age was physical activity which was associated with reduced risk of total, premature and late mortality (range of HRs when comparing the highest vs. the lowest level: 0.24 to 0.48). Specific strong predictors for premature mortality were smoking, HR: 4.22 (95 % CI: 2.42-7.38), and the concurrence of ≥2 metabolic conditions at baseline, HR: 1.97 (1.10-3.51). The habit of sleeping a long nap (≥30 min/d), with HR: 2.53 (1.30-4.91), and poor adherence to the Mediterranean Diet (≤3 points in a 0 to 8 score vs. ≥6 points), with HR: 2.27 (1.08-4.76), were the strongest specific predictors for late mortality. Smoking, diet quality or lifestyles, probably should be differentially assessed as specific predictors for early and late mortality. In the era of precision medicine, this approach will allow tailored recommendations appropriate to each person's age and baseline condition.

Daytime naps and depression risk: A meta-analysis of observational studies

Background

The relationship between daytime napping and depression remains debatable. Thus, a meta-analysis in this study was conducted to evaluate the relationship between daytime napping and depression.

Methods

The PubMed, Embase, Web of Science, and China National Knowledge Infrastructure databases were searched up to February 2022, and the reference lists of the included studies were also retrieved. A random-effects model was used to estimate the combined effect size.

Results

Nine studies with 649,111 participants were included in the final analysis. The pooled odds ratio (OR) was 1.15 (95% confidence interval: 1.01-1.31) with a significant heterogeneity (I ² = 91.3%, P for heterogeneity <0.001), and the results demonstrated an increased risk of depressive symptoms among daytime nappers. Visual inspection of the funnel plot and Egger's and Begg's tests identified no obvious evidence of publication bias.

Conclusion

This meta-analysis indicates that daytime naps are a predictor of depression. The effects of daytime napping on depression may vary depending on the characteristics of people, the pattern of naps, and the individual's sleep experience. The findings may have significant implications for future research on depression.

Bidirectional Associations between Daytime Napping Duration and Metabolic Syndrome: A Nationally Representative Cohort Study

BACKGROUND

We aimed to examine the bidirectional associations between daytime napping duration and metabolic syndrome (MetS).

METHODS

Using data from the China Health and Retirement Longitudinal Study from 2011 to 2015, modified Poisson regression models were performed to explore the longitudinal associations of baseline napping duration with the occurrence and remission of MetS. Generalized estimating equation was conducted to explore the association between baseline MetS status with subsequent changes in daytime napping duration. Cross-lagged panel analysis was performed to further verify their bidirectional relationships.

RESULTS

During the four-year follow-up, among 5041 participants without MetS at baseline, extended naps were significantly associated with MetS occurrence, compared with non-napping. This association was only significant in individuals with adequate night-time sleep duration or good sleep quality of the 2898 participants with MetS at baseline. Excessive napping duration may be not favorable for MetS remission especially for adequate night-time sleepers. With respect to reverse associations, baseline MetS status significantly increased the napping duration during the subsequent follow-up period. Finally, there were significant bidirectional cross-lagged associations between napping duration and MetS severity score after adjusting for all covariates.

CONCLUSIONS

Our study indicates bidirectional relationships exist between daytime napping duration and MetS. Interestingly, longer napping duration was detrimental to cardiometabolic health only in those with sufficient night-time sleep duration or good sleep quality.

The "jolly fat" for the middle-aged and older adults in China, was education level considered?

BACKGROUND

Several studies have found a negative association between obesity and depression in Chinese middle-aged and elderly, suggesting the existence of "jolly fat". This study aims to investigate whether "jolly fat" is applicable among middle-aged and elderly with different education levels, and to provide a new perspective for depression screening and obesity interventions in middle-aged and older adults.

METHODS

10,018 individuals aged 45 years and over in China Family Panel Study (2018) were selected for analysis. A short version of Center for Epidemiological Research Depression Scale was used to assess depression. Body mass index was applied to define obesity status. Subgroup analysis of multiple logistic regression was performed to explore whether the relationship between obesity and depression was influenced by education levels.

RESULTS

The prevalence of obesity and depression was 9.02 % and 22.96 % among participants. Obesity reduced the probability of depression in middle-aged and elderly with primary school education or below (OR = 0.71, 95 % CI = 0.56-0.91) while not affecting those with junior high school education or above (OR = 0.80, 95 % CI = 0.57-1.13).

LIMITATIONS

The results cannot be interpreted as causality due to the cross-sectional design. Besides, we cannot directly measure the body composition of the participants.

CONCLUSIONS

"Jolly fat" existed among middle-aged and elderly with low education, but not in those with junior high school education or above. Health care providers need to monitor the psychological status of low-educated middle-aged and older adults who are seen as needing to lose weight, while the underweight group should be the key target of depression screening.

Sleep Factors in Relation to Metabolic Dysfunction-Associated Fatty Liver Disease in Middle-Aged and Elderly Chinese

CONTEXT

Accumulating evidence implies that sleep disturbance is involved in metabolic disorders.

OBJECTIVE

We comprehensively evaluated the association between various dimensions of sleep behaviors and the risk for metabolic dysfunction-associated fatty liver disease (MAFLD).

METHODS

In this cross-sectional study of 5011 participants with self-reported sleep behaviors and radiologically diagnosed MAFLD, a comprehensive healthy sleep score was generated to evaluate the associations between sleep behaviors and MAFLD risk using multivariate logistic regression adjusting for demographics, lifestyles, medication, and metabolic comorbidities. Furthermore, mediation analysis was utilized to assess the extent to which obesity explains the effect of sleep quality on MAFLD risk.

RESULTS

Late bedtime, snoring, and daytime napping for over 30 minutes significantly associated with an increased risk of MAFLD, with odds ratios (OR) of 1.37 (95% CI 1.10, 1.70), 1.59 (95% CI 1.33, 1.91), and 1.17 (95% CI 1.02, 1.35), respectively, after full adjustments including obesity. Participants with disturbance in nighttime sleep and prolonged daytime napping showed the highest risk for MAFLD (OR 2.38, 95% CI 1.73, 3.27). Each additional increase of healthy sleep score was associated with a 16% reduction in MAFLD risk. Further stratified analysis revealed that people with a sedentary lifestyle and central obesity experienced more prominent adverse effects from poor sleep quality than others. Moreover, obesity accounted for only 20.77% of the total effect of sleep quality on MAFLD risk.

CONCLUSIONS

Sleep behaviors, both cumulatively and individually, are associated with MAFLD risk. Public health awareness and strategies should be encouraged to curb MAFLD.

Obesity indicators as mediators of association between daytime napping and type 2 diabetes mellitus: the Guangzhou Biobank Cohort Study

OBJECTIVE

To examine the mediating effect of obesity indicators on the association between daytime napping and type 2 diabetes mellitus (T2DM) qualitatively and quantitatively using baseline data from the Guangzhou Biobank Cohort Study.

METHODS

Twenty-nine thousand three hundred fifty-five participants aged 50+ years were included in this cross-sectional study. Mediation analysis was used to assess the mediating effect of body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) on the association between daytime napping and T2DM after adjustment for sex, age, education, occupation, smoking status, alcohol use and physical activity.

RESULTS

The mean (standard deviation) age of participants was 61.5 ( 7.1) years. The prevalence of T2DM and daytime napping was 12.5% and 65.2%, respectively. After adjustment for potential confounders, WC, WHR and WHtR showed partial mediating effects on the association between daytime napping and T2DM, with the proportion (95% confidence interval) of mediation effect being 10.17% (8.14-14.43%), 14.91% (11.95-21.24%) and 9.36% (7.49-13.29%), respectively. No mediating effect of BMI or HC on the association between daytime napping and T2DM was found.

CONCLUSIONS

Our results showed significant mediating effects of WC, WHR and WHtR on the association between daytime napping and T2DM, suggesting that waist circumference management could be important in daytime nappers.

Association of Daytime Napping with chronic diseases among Tibetan people in China: a cross-sectional study

BACKGROUND

Obesity, diabetes, and hypertension, as three of the most prevalent chronic diseases, remain a daunting health challenge. However, to our knowledge, no study has made a thorough examination of the association between the three chronic diseases and daytime napping, a widely accepted behavior in many countries. This is especially necessary among Tibetan populations, whose lifestyles and health outcomes may be unique, yet patterns of chronic diseases and napping are under-examined. Thus, we sought to explore the aforementioned association in the Tibetan population of China.

METHODS

A total of 2902 participants aged 45-79 in 2019 were included. Multivariate logistic regressions were conducted in 2020. The sex disparity was examined through interaction and stratified analyses.

RESULTS

Hypertension (40.7%) was more prevalent than obesity (20.2%) and diabetes (21.6%). Comparing to non-nappers, those who napped were more likely to have any conditions (OR = 1.30, 95% CI = 1.04-1.62 for 1-59 min/day group and OR = 1.40, 95% CI = 1.10-1.80 for ≥60 min/day group). Participants who had 1-59 min/day of napping were more likely to develop obesity (OR = 1.37, 95% CI = 1.07-1.75), and ≥ 60 min/day of napping was associated with diabetes (OR = 1.33, 95% CI = 1.01-1.74). The interactions between napping and sex were not statistically significant in the models.

CONCLUSIONS

The study revealed napping was unfavorably associated with obesity, diabetes, and any conditions in Tibetan people living on the Tibetan Plateau. Future interventions regarding the three chronic diseases may pay more attention to napping.

TRIAL REGISTRATION

Not applicable.

Sleep duration and anthropometric indices in an Iranian population: the Fasa PERSIAN cohort study

Recent decades have seen a dramatic rise in the prevalence of obesity. While genetic factors can influence obesity, environmental factors and lifestyle may play important roles as well. Sleep can be regarded as one of these factors. This study aimed to examine sleep duration, as a potential risk factor for obesity in an Iranian population. In this cross-sectional study, the Fasa PERSIAN cohort study data was used and 10,136 subjects aged 35-70 were entered. Anthropometrics indices have been measured and the total body fat percentage (BFP) was obtained by Bio-Impedance Analysis. Also, physical activity and dietary intake have been recorded. Sleep duration was obtained and individuals categorized into two groups of "< 8" and "≥ 8" h of sleep. The mean age and sleep duration of the participants were 48.63 ± 9.57 years and 6.92 ± 1.62 h in the total population, respectively. All of the anthropometric indices were significantly higher in the "< 8 h of sleep" group than in the "≥ 8 h of sleep" group. Regarding BFP and fat mass index (FMI) the same results was seen (p-value < 0.05). Body mass index (BMI), Waist and hip circumferences (WC, HC), and waist-to-height ratio (WHtR) were in a significant negative association with night time sleep (p-value < 0.001), while these associations with daytime napping were positive (p-value < 0.001). After multi-variable adjusting, BMI, WC, HC, WHtR, and wrist circumference showed significant negative associations with 24-h sleep duration (p-value < 0.05). This study established the association between nocturnal, daytime napping, 24-h sleep duration and obesity parameters. Daytime napping was positively associated with obesity parameters and short 24-h sleep duration was associated with higher risk of overweight/obesity. These results indicate that insufficient sleep can be a screening indicator for an unhealthy lifestyle and poor health outcomes.