Sleep duration affects health in various ways. The objective of the present study was to investigate the relationships among sleep duration, daytime napping and kidney function in a middle-aged apparently healthy Chinese population. According to self-reported total sleep and daytime napping durations, 33,850 participants who were 38–90 years old and recruited from eight regional centers were divided into subgroups. Height, weight, waist circumference, hip circumference, blood pressure, biochemical indexes, fasting blood glucose (FBG), postprandial blood glucose (PBG), HbA1c, creatinine and urinary albumin-creatinine ratio (UACR) were measured and recorded for each subject. Microalbuminuria was defined as UACR ≥30 mg/g, chronic kidney disease (CKD) was defined as eGFR 9 h/day, 8–9 h/day 6–7 h/day and <6 h/day were 1.343 (1.228–1.470, P<0.001), 1.223 (1.134–1.320, P<0.001), 1.130 (1.003–1.273, P = 0.045) and 1.140 (0.908–1.431, P = 0.259), respectively. The eGFR levels exhibited a U-shaped association with sleep duration among subjects with an eGFR ≥90 ml/min and an N-shaped association with sleep duration among subjects with an eGFR 9 h/day of sleep was 1.400 (1.123–1.745, P = 0.003) among participants with an eGFR ≥90 ml/min. Daytime napping had a negative effect on renal health. Compared to the absence of a napping habit, the ORs for microalbuminuria for 0–1 h/day, 1–1.5 h/day and >1.5 h/day of daytime napping were 1.552 (1.444–1.668, P<0.001), 1.301 (1.135–1.491, P<0.001) and 1.567 (1.353–1.814, P<0.001), respectively. The association of total sleep duration with renal health outcomes is U-shaped. Daytime napping has a negative effect on renal health.

Dyslipidaemia has always been regarded as the cornerstone of arteriosclerosis and is related to the pathogenesis of renal insufficiency. However, it is unclear which routinely available lipid parameter is related to urinary albumin to creatinine ratio (UACR). The purpose of this study was to examine the lipid abnormalities associated with UACR in the general population in China. The present study was nested in an ongoing Risk Evaluation of cAncers in Chinese diabetic Individuals: A lONgitudinal (REACTION) study, which was designed to demonstrate the association of abnormal glucose metabolism with the risk of cancer in the Chinese population. This cross-sectional study included 34, 569 subjects (11, 390 males and 23, 179 females) from 8 different regional community cohorts, with an average age of 57.9 years. The UACR data were divided into the < 25% group, the 25–49% group, the 50–74% group, and the ≥ 75% group according to the quartile division of the centre where the subjects visited. The lipid classes were defined according to the guidelines for the prevention and treatment of dyslipidaemia in Chinese adults. Multiple logistic regression analysis was used to evaluate the association of the lipid parameters and UACR. Multivariable regression analysis revealed that compared with the other lipid parameters, triglycerides (TG) showed an adjusted odds ratio that was significant in model 1–4. This relationship was attenuated after adjusting for Haemoglobin A1c (HbA1c) and blood pressure (BP), but TG ≥ 2.3 mmol/L was still significantly associated with UACR in total subjects and in both men and women (OR: 1.131, 95% CI 1.065–1.203, P < 0.001 in total subjects; OR: 1.134, 95% CI 1.022–1.258, P = 0.017 in men; OR: 1.129, 95% CI 1.046–1.219, P = 0.002 in women). In the stratified analysis, elevated TG was significantly associated with increased urinary albumin in subjects with eGFR ≥ 90 mL/min per 1.73 m2, 5.6 ≤ FBG < 7.0 or 7.8 ≤ PBG < 11.1 mmol/L, 24 ≤ BMI < 28 kg/m2, 120 ≤ SBP < 140 and/or 80 ≤ DBP < 90 mmHg. We conclude that high TG levels rather than total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or non-high-density lipoprotein cholesterol levels are associated with UACR in the general population in China.

Background: Sleep duration affects health in various way. The objective of this study was to investigate the relationship between sleep duration, daytime napping and kidney function in a middle-aged apparently healthy Chinese population. Methods: According to self-reported total sleep and daytime napping duration, 33,850 participants aged 38 to 90 years old from 8 regional centers were divided into subgroups. Height, weight, waistline, hipline, blood pressure, biochemical index, FBG, PBG, HbA1c, creatinine and urinary albumin-creatinine ratio (UACR) were measured and recorded in each subject. Microalbuminuria was defined as UACR>=30 mg/g, CKD was defined as eGFR=135 ml/min. Multiple logistic regressions were applied to investigate associations between sleep and kidney function. Results: Compared to participants with [7-8]h/day sleep, ORs of >9 h/day, (8, 9]h/day and <6h/day sleep for microalbuminuria were 1.317 (1.200-1.446, p<0.001), 1.215 (1.123-1.315, p=90ml/min eGFR, and N-shaped associated with sleep duration among subjects with 9h/day sleep for hyperfiltration was 1.400 (1.123-1.745, p=0.003) among eGFR>=90 ml/min participants. Daytime napping had a negative effect on renal health. Compared to participants did not have napping habit, the ORs of (0, 1]h/day, (1, 1.5]h/day and >1.5h/day daytime napping for microalbuminuria were 1.477 (1.370-1.591, p<0.001), 1.217 (1.056, 1.403, p=0.007) and 1.447 (1.242, 1.687, p<0.001). Conclusions: Total sleep duration are U-shaped associated with renal health outcomes. Daytime napping had a negative effect on renal health.