Lifestyle mediators of associations among siestas, obesity, and metabolic health

Abstract

Objective The aim of this study was to determine the association between siestas/no siestas and obesity, considering siesta duration (long: >30 minutes, short: ≤30 minutes), and test whether siesta traits and/or lifestyle factors mediate the association of siestas with obesity and metabolic syndrome (MetS). Methods This was a cross‐sectional study of 3275 adults from a Mediterranean population (the Obesity, Nutrigenetics, TIming, and MEditerranean [ONTIME] study) who had the opportunity of taking siestas because it is culturally embedded. Results Thirty‐five percent of participants usually took siestas (16% long siestas). Compared with the no‐siesta group, long siestas were associated with higher values of BMI, waist circumference, fasting glucose, systolic blood pressure, and diastolic blood pressure, as well as with a higher prevalence of MetS (41%; p = 0.015). In contrast, the probability of having elevated SBP was lower in the short‐siesta group (21%; p = 0.044) than in the no‐siesta group. Smoking a higher number of cigarettes per day mediated the association of long siestas with higher BMI (by 12%, percentage of association mediated by smoking; p < 0.05). Similarly, delays in nighttime sleep and eating schedules and higher energy intake at lunch (the meal preceding siestas) mediated the association between higher BMI and long siestas by 8%, 4%, and 5% (all p < 0.05). Napping in bed (vs. sofa/armchair) showed a trend to mediate the association between long siestas and higher SBP (by 6%; p = 0.055). Conclusions Siesta duration is relevant in obesity/MetS. Timing of nighttime sleep and eating, energy intake at lunch, cigarette smoking, and siesta location mediated this association.

Wake up! It's time to recognize the importance of sleep in metabolic health

“…For example, prescription of nightly bed and wake times to improve sleep regularity may be preferrable to napping; preliminary research showed favorable effects on body composition of stabilizing sleep [40], whereas a study in this special section showed that long naps, relative to no naps, were associated with higher odds for metabolic syndrome and markers of poor metabolic health [41]. Even with these examples,…”

“…However, there is also an urgent need for well‐designed clinical trials to evaluate the efficacy of sleep health interventions in promoting metabolic health to inform evidence‐based practices. For example, prescription of nightly bed and wake times to improve sleep regularity may be preferrable to napping; preliminary research showed favorable effects on body composition of stabilizing sleep [40], whereas a study in this special section showed that long naps, relative to no naps, were associated with higher odds for metabolic syndrome and markers of poor metabolic health [41]. Even with these examples, additional testing is needed to inform recommendations.…”

Circadian desynchrony and glucose metabolism

“…102 A large cross-sectional study in a Mediterranean population found that long siestas (>30 min) were associated with higher body mass index (BMI) and higher fasting glucose. 103 In addition, long siesta nappers had delayed sleep, meal timing and physical activity behavior and had a later chronotype compared to the short-siesta nappers and nonnappers. 103 Mendelian randomization studies published in 2022-2023 have demonstrated a strong association between frequent insomnia symptoms and insulin resistance, increased HbA1c and risk of type 2 diabetes.…”

“…103 In addition, long siesta nappers had delayed sleep, meal timing and physical activity behavior and had a later chronotype compared to the short-siesta nappers and nonnappers. 103 Mendelian randomization studies published in 2022-2023 have demonstrated a strong association between frequent insomnia symptoms and insulin resistance, increased HbA1c and risk of type 2 diabetes. 104,105 Experimental studies in a controlled environment in humans found that sleep deprivation impairs glucose tolerance 106,107 and insulin sensitivity in muscle.…”

Association of impaired sensitivity to thyroid hormones with hyperuricemia through obesity in the euthyroid population

“…Currently, there is a lack of interventions to address impaired sensitivity to thyroid hormones. It is noteworthy that mediation analysis can reveal indirect pathways for potential intervention strategies, particularly through nonpharmaceutical and modifiable factors such as lifestyle changes [ 32 , 33 ].…”