The interactive effect of habitual midday napping and nighttime sleep duration on impaired fasting glucose risk in healthy adolescents

Association between napping and type 2 diabetes mellitus

As the incidence of type 2 diabetes mellitus (T2DM) is increasing rapidly and its consequences are severe, effective intervention and prevention, including sleep-related interventions, are urgently needed. As a component of sleep architecture, naps, alone or in combination with nocturnal sleep, may influence the onset and progression of T2DM. Overall, napping is associated with an increased risk of T2DM in women, especially in postmenopausal White women. Our study showed that napping >30 minutes (min) increased the risk of T2DM by 8-21%. In addition, non-optimal nighttime sleep increases T2DM risk, and this effect combines with the effect of napping. For nondiabetic patients, napping >30 min could increase the risks of high HbA1c levels and impaired fasting glucose (IFG), which would increase the risk of developing T2DM later on. For diabetic patients, prolonged napping may further impair glycemic control and increase the risk of developing diabetic complications (e.g., diabetic nephropathy) in the distant future. The following three mechanisms are suggested as interpretations for the association between napping and T2DM. First, napping >30 min increases the levels of important inflammatory factors, including interleukin 6 and C-reactive protein, elevating the risks of inflammation, associated adiposity and T2DM. Second, the interaction between postmenopausal hormonal changes and napping further increases insulin resistance. Third, prolonged napping may also affect melatonin secretion by interfering with nighttime sleep, leading to circadian rhythm disruption and further increasing the risk of T2DM. This review summarizes the existing evidence on the effect of napping on T2DM and provides detailed information for future T2DM intervention and prevention strategies that address napping.

Association of sleep behaviors, insulin resistance surrogates, and the risk of hypertension in Chinese adults with type 2 diabetes mellitus

Objective

Our aim was to evaluate the association between midday napping, combined sleep quality, and insulin resistance surrogates and the risk of hypertension in patients with type 2 diabetes mellitus (T2DM).

Methods

Data were collected using a standardized questionnaire. Binary logistic regression was performed to estimate the odds ratio (OR) and 95% confidence interval (CI) for the risk of hypertension. Systolic and diastolic blood pressure were grouped as categorical variables and unpaired two-sided Student's t-test and Spearman correlation analysis were performed to estimate the association between different blood pressure levels and insulin resistance surrogates.

Results

The overall prevalence rate of hypertension was 50%. Age (OR = 1.056, 95% CI:1.044-1.068), poor sleep quality (OR = 1.959, 95% CI:1.393-2.755), hyperlipidemia (OR = 1.821, 95% CI:1.462-2.369), family history of hypertension (OR = 2.811, 95% CI:2.261-3.495), and obesity (OR = 5.515, 95% CI:1.384-21.971) were significantly associated with an increased risk of hypertension. Midday napping for 1-30 min was negatively correlated with the risk of hypertension (OR = 0.534, 95% CI:0.305-0.936, P <0.05).

Conclusion

Poor sleep quality and obesity are independent risk factors for hypertension. Midday napping (1-30 min) is associated with a decreased risk of hypertension in patients with T2DM.

Habitual nappers and non-nappers differ in circadian rhythms of LIPE expression in abdominal adipose tissue explants

Background and purpose

Napping is a widespread practice worldwide and has in recent years been linked to increased abdominal adiposity. Lipase E or LIPE encodes the protein hormone-sensitive lipase (HSL), an enzyme that plays an important role in lipid mobilization and exhibits a circadian expression rhythm in human adipose tissue. We hypothesized that habitual napping may impact the circadian expression pattern of LIPE, which in turn may attenuate lipid mobilization and induce abdominal fat accumulation.

Methods

Abdominal adipose tissue explants from participants with obesity (n = 17) were cultured for a 24-h duration and analyzed every 4 h. Habitual nappers (n = 8) were selected to match non-nappers (n = 9) in age, sex, BMI, adiposity, and metabolic syndrome traits. Circadian LIPE expression rhythmicity was analyzed using the cosinor method.

Results

Adipose tissue explants exhibited robust circadian rhythms in LIPE expression in non-nappers. In contrast, nappers had a flattened rhythm. LIPE amplitude was decreased in nappers as compared with non-nappers (71% lower). The decrease in amplitude among nappers was related to the frequency of napping (times per week) where a lower rhythm amplitude was associated with a higher napping frequency (r = -0.80; P = 0.018). Confirmatory analyses in the activity of LIPE's protein (i.e., HSL) also showed a significant rhythm in non-nappers, whereas significance in the activity of HSL was lost among nappers.

Conclusion

Our results suggest that nappers display dysregulated circadian LIPE expression as well as dysregulated circadian HSL activity, which may alter lipid mobilization and contribute to increased abdominal obesity in habitual nappers.

Sleep and Type 1 Diabetes Mellitus Management Among Children, Adolescents, and Emerging Young Adults: A Systematic Review

BACKGROUND

Type 1 diabetes mellitus (T1DM) is one of the most common chronic illnesses among the youth. Emerging evidence has suggested poor sleep as a risk factor for glycemic control. This review aimed to examine the associations between sleep characteristics and diabetes management in children, adolescents, and emerging young adults with T1DM.

METHODS

Following PRISMA guidelines, the authors searched articles in PubMed, Web of Science, and Scopus from 2000 through August 2020. Using inclusion and exclusion criteria, observational studies and clinical trials that examined sleep and diabetes management among individuals with T1DM (up to 25 years old) were selected for review.

RESULTS

Twenty-four articles met the review criteria. Most studies did not report differences in self-report sleep between individuals with and without T1DM. However, several studies using objective sleep measures (actigraph and PSG) suggested shorter sleep duration and worse sleep quality in individuals with T1DM. Higher A1C levels and undesirable T1DM self-care behaviors were associated with short and long sleep duration, poor sleep quality, sleep disturbances, and irregular sleep, particularly among adolescent boys, young men and those from immigrant families. Self-care behaviors mediated the associations between sleep and subsequent A1C levels.

CONCLUSIONS

Too much or too little sleep, poor sleep quality, sleep disturbances and sleep variability are associated with undesirable T1DM management. Although more research is needed, our findings indicate the importance of including sleep education in the plan of care for children, adolescents and emerging young adults with T1DM.

Using propensity score matching with doses in observational studies: An example from a child physical abuse and sleep quality study

Both physical abuse and poor sleep quality are public health concerns among adolescents, particularly in mainland China, but examining any causal effect of physical abuse on adolescents' sleep quality using a randomized controlled trial is not possible for obvious ethical reasons. Researchers have proposed the use of propensity score matching with doses to minimize overt bias and estimate the effect of multidose treatments or varying degrees of risk exposure in observational studies. In this paper, we demonstrate the propensity score methods with a focus on matching with doses in an examination of the relationship between physical abuse levels (frequency and number of perpetrators) and self-reported sleep quality among adolescents. Secondary analyses were conducted using data from the China Jintan Child Cohort. The sample comprised 707 adolescents (13.16 ± 0.90 years old) who had complete data on physical abuse, sleep, and covariates. Propensity scores were computed from eight covariates and used to carry out pair matching, matching with the frequency of abusive experience, and matching with the number of perpetrators. The standardized differences of covariates suggested an acceptable balance between groups after matching. The results derived from matching sets consistently indicated that adolescents being physically abused by parent(s) have worse sleep quality. Despite its inherent limitations, propensity score matching with doses provides a useful tool for nurse researchers analyzing observational data.