Effects Of Dietary Intake Of Trace Elements Iron,Copper,Zinc And Selenium On Sleep Disorders In Elderly

Objective: Sleep is closely related to everyone’s life.As a global problem,sleep disorders are much more common in the elderly than in other groups.Most current studies on diet and sleep focus on macronutrients,fatty acids and carbohydrates.A small amount of trace elements can play an important role in the normal operation of all aspects of the body.There are a few and controversial studies on iron,copper,zinc,selenium and sleep disorders in old age.This study is a cross-sectional study.Exploring the correlation between the intake of iron,copper,zinc and selenium in the elderly and various types of sleep disorders and sleep quality,NHANES data were selected to provide reference basis for improving the sleep quality of the elderly or for the treatment of sleep disorders in the elderly.Methods: The data of this study were obtained from the 2007-2008 NHANES database,and the elderly people over 60 years old were selected as the study subjects.Subjects with only one dietary recall,missing data on sleep,not within the range of ±3 SD,and missing data on BMI were excluded.The included variables have gender,age,race,education level,living alone,BMI,smoking,drinking,hypertension,diabetes,energy,caffeine,iron,copper,zinc,selenium,sleep duration,sleep onset latency,obstructive sleep apnea(OSA),sleep problem,day sleepiness,and sleep quality.IBM SPSS 26 and STATA/SE15.1 statistical software were used for statistical analysis.When continuous variables show a normal distribution,we can describe them using mean ± standard deviation and compare differences between groups using the independent sample T-test and one-way analysis of variance.When the continuous variables were not normal distribution,median and quartile spacing were used to describe them,and nonparametric tests were used to compare the differences between groups.The chi-square test was used to contrast the rates or constituent ratios of categorical variables between groups.Data were weighted by the Taylor linearized method,and unconditional logistic regression was used to explore the relationship between the quartiles of iron,copper,zinc,and selenium intake and sleep duration,sleep onset latency,OSA,sleep problem,day sleepiness,and sleep quality under univariate and multivariate models.The subjects were stratified by gender,and unconditional logistic regression was used to explore the association between the intake of four trace elements and different types of sleep and sleep quality in different genders under univariate and multivariate models.According to the recommended intake of the four trace elements,they were divided into two groups.Multiplicative interaction model was used to analyze the interaction between the presence of the four trace elements in different sleep types.Results: A total of 1358 subjects were included in this study,including 703 males(51.77%)and 655 females(48.23%).The unconditional logistic regression was used to explore the relationship between the intake of iron,copper,zinc,selenium and sleep duration,sleep onset latency,OSA,sleep problems,day sleepiness,sleep quality.Under univariate and multivariate conditions,compared with the lowest quantile group,the increase of selenium intake in the third quantile group was associated the low risk of sleep duration>8h/night,and the OR(95%CI)was 0.25(0.13,0.47),0.28(0.14,0.55)and 0.42(0.18,0.97),respectively.Both univariate and multivariate logistic regression showed that compared with the lowest quantile group,the increase of iron intake in the highest quantile group was associated with the high risk of sleep onset latency <6 minutes /night,and the OR(95%CI)was 2.28(1.35,3.83),2.29(1.30,4.05),1.94(1.17,3.21),respectively.Both univariate and multivariate logistic regression showed that compared with the lowest quartile,the increase of zinc intake in the second and fourth quartile groups was associated with the low risk of sleep onset latency>30min/night,and there is a negative correlation.Unconditional logistic regression stratified by gender was used to explore the relationship between the intake of iron,copper,zinc,selenium and sleep duration,sleep onset latency,OSA,sleep problems,day sleepiness,sleep quality.We created univariate(unadjusted)and multivariate(adjusted for age,race,education,living alone,BMI,smoking,drinking,hypertension,diabetes,energy,caffeine)models.The following results are confirmed in univariate and multivariate conditions.Compared with the lowest quantile group,the increase intake of zinc in the highest quantile group will reduce the risk of sleep duration<7h/night in women,the OR(95%CI)was 0.38(0.17,0.84)and 0.42(0.19,0.93).The inverse associations of sleep duration<7h/night in women were statistically significant for the highest quartile versus lowest quartile of selenium intake,OR(95%CI)0.24(0.11,0.49)、0.17(0.06,0.48).Compared with the lowest quantile group,the increase intake of selenium in the second quantile group will reduce the risk of sleep duration>8h/night in women,the OR(95%CI)was 0.25(0.08,0.73)、0.27(0.08,0.89).The increase of zinc intake in the second quantile group will reduce the risk of sleep onset latency>30min/night in women,OR(95%CI)0.46(0.27,0.79)、0.39(0.20,0.78).Conclusion: Increased iron intake may be associated with an increased risk of sleep onset latency<6min/night.Increased selenium intake may be associated with decreased risk of abnormal sleep duration in women.In women,increased zinc intake was associated with a reduced risk of sleep duration <7h/night and sleep duration >30min/night.