Associations between vegetable and fruit intake and sleep duration among Chinese adults aged over 80 years: an analysis based on the China Nutrition and Health Surveillance, 2015–2017

Objective To explore the relationship between vegetable and fruit intake and sleep duration among Chinese adults aged over 80 years, thereby providing a scientific basis for improving sleep quality in this population.

Methods Multistage stratified cluster random sampling was conducted for data from the China Nutrition and Health Surveillance (2015–2017). A total of 2319 elderly participants from 31 provinces (autonomous regions, municipalities directly under the Central Government) in China were selected to complete a questionnaire survey, physical measurements, and laboratory tests. The average daily intake of vegetables, fruits, and total vegetable and fruit intake was investigated, and the population was divided into quintiles in ascending order. Those with the daily sleep duration of 7–9 h were defined as the healthy sleep duration group, and those with the daily sleep duration of < 7 h or > 9 h were defined as the unhealthy sleep duration group. Multivariate unconditional logistic regression was adopted to explore the association between the two. Restricted cubic spline (RCS) analysis was performed to explore the dose-response relationship between fruit and vegetable intake and unhealthy sleep duration.

Results Among the 2319 elderly participants in China, 52.13% had unhealthy sleep duration. Different sleep duration groups varied in sex (χ² = 6.672), place of residence (χ² = 8.422), educational background (χ² = 15.573), per capita annual household income (χ² = 23.021), marital status (χ² = 8.894), physical activity level (χ² = 9.873), and sedentary behavior distribution (χ² = 6.631) (all P < 0.05). In addition, there were also differences in age (t = 2.220), vegetable intake (t = 3.420), fruit intake (t = 3.470), and total vegetable and fruit intake (t = 4.190) among different groups (all P < 0.05). Multivariate unconditional logistic regression showed that after adjusting for age, sex, BMI, place of residence, educational background, per capita annual household income, marital status, number of cohabitants, current smoking, current alcohol consumption, physical activity level, sedentary behavior, participation in health checkups within the past year, and the prevalence of hypertension, diabetes, and dyslipidemia, vegetable intake, fruit intake, and total vegetable and fruit intake were negatively associated with the risk of unhealthy sleep duration. Compared with the lowest group, the highest group showed reductions of 26% (vegetable intake: OR = 0.74, 95%CI: 0.56–0.97), 28% (fruit intake: OR = 0.72, 95%CI: 0.55–0.95), and 29% (total fruit and vegetable intake: OR = 0.71, 95%CI: 0.54–0.94) in the risk of unhealthy sleep duration (all P_trend < 0.05). RCS analysis revealed that both fruit intake and total vegetable and fruit intake had significantly negatively linearly associations with unhealthy sleep duration (both P_{non-linearity} ≥ 0.05).

Conclusions The vegetable intake, fruit intake, and total vegetable and fruit intake are negatively correlated with the risk of unhealthy sleep duration in Chinese adults aged 80 and above. The findings provide a potential intervention target to promote healthy sleep duration in this population.