Association between nighttime sleep and successful aging among older Chinese people

Highlights

• Most Chinese older adults experience insufficient sleep and poor sleep quality.

• Sleep is closely associated with successful aging among older adults.

• The association between sleep and successful aging is related to age and gender.

Abstract

Objective

This study aims to assess the association between sleep and successful aging among Chinese ≥60 years of age.

Methods

Data were collected from the baseline survey of the China Health and Retirement Longitudinal Study. Two self-reported questions about sleep quality and duration were examined. Successful aging was defined following Rowe and Kahn's multidimensional model. To assess the adjusted association between sleep and successful aging, multivariable logistic regression was applied.

Results

The average number of self-reported hours of sleep was 6.2 ± 2.0 among older Chinese people. Successful aging was related to sleep duration, with the proportion of those adults considered to be aging successfully falling into the following sleep duration categories (<6 h – 7.8%; 6 h – 16.3%; 7 h – 19.1%; 8 h – 14.7%; and ≥9 h – 12.8%). The plots between sleep duration and successful aging were an inverse U-shape. Participants who slept less than 6 h per day had lower odds ratios of successful aging [odds ratio (OR) = 0.52, 95% confidence interval (CI) 0.40–0.67] relative to those who slept for 7 h per day. Compared with those who reported poor sleep less than once a week, older people who reported poor sleep five to seven days a week showed a lower ratio of successful aging (OR = 0.29, 95% CI 0.21–0.39).

Conclusion

Older age, shorter or longer sleep, and poor sleep were related to lower odds of, rates of successful aging. Most older Chinese adults experience insufficient sleep and poor sleep quality, which could be an important influential factor in successful aging.

Introduction

China's population is aging rapidly, with 212 million people aged 60 years and over accounting for 15.5% of the total population in 2014. In China, life expectancy at birth has increased from 69 years in 1990 to 75 years in 2013 [1]. If people do not age successfully, living longer may contribute to increased dependency on others/family and poor quality of life. Successful aging is a desirable goal for older people that encompasses the absence of disease, high psychological and physical functioning, and active engagement with life [2], [3]. This definition of successful aging has been perceived as a useful tool for describing the health status of the elderly population and labeled as a “calculable gold standard of aging” [4] according to many empirical studies performed today [5].

Nighttime sleep is an essential physiological process for good health that aids/utilizes vital restorative functions [6], [7]. As people age, they experience shortened and less restorative sleep, more frequent nighttime awakenings, increased time awake during the night, and more early morning awakenings [8]. Older age is associated with increased sleep problems [9], [10], [11] and shorter sleep duration [12], [13], which suggests that sleep difficulties could particularly be salient issues among older adults. Furthermore, older women have poorer sleep quality and shorter sleep duration than men [9], [14]. This gender difference in sleep quality could be relevant to the gender difference associated with the relationship between sleep and health.

Sleep patterns in Chinese older adults may be characterized by going to bed early and waking up early [9]. Recent studies have reported that the prevalence of poor sleep was 41.5% among urban populations [15] and 49.7% among rural populations [16], and sleep duration was between 5.5 and 7.5 h among eldery Chinese individuals/adults [9], [14], [17]. Poor sleep quality and short or long sleep duration are associated with many diseases or health conditions, such as metabolic syndrome [18], obesity [19], hypertension [20], memory impairment [21], diabetes [22], cardiovascular diseases [23], and mortality [24], [25]. In contrast, good sleep is a marker of good functioning across a variety of domains in old age [26]. To date, most studies assessing the association of sleep with health have focused on a single disease or condition. Examining a multidimensional construct such as successful aging could provide an improved insight into the association between sleep and overall health. However, the association between sleep and successful aging has not been previously examined. This study aims to examine the association of sleep duration and/or sleep quality with successful aging using a nationally representative sample from the China Health and Retirement Longitudinal Study (CHARLS). Our study will provide evidence on the relationship between sleep and successful aging in the Chinese population.