UNIVERSITY PARK, Pa. — India is home to more than 150 million people over the age of 60. This figure will more than double by 2050, reaching roughly the current total population of the United States, according to projections from the United Nations Population Fund. In order to promote well-being and health as people age, researchers in the Penn State Department of Human Development and Family Studies (HDFS) and Center for Healthy Aging examined the relationship between sleep and frailty — the declining strength and robustness associated with aging — among older adults in India.  

The researchers found that older people in India who reported low-quality sleep were almost three times more likely to be frail. The team also found that older Indian men who sleep nine or more hours per night were less likely to be frail, contrary to their expectation that seven to eight hours would be the healthiest amount of sleep for all older adults.  

“The scope of India’s need to care for aging adults is going to increase dramatically in the coming years," Muhammad said. “But this problem is not unique to India. The global aging population is growing, with the most rapid increases in low- and middle-income countries. Sleep could be the key to preventing or delaying frailty, a major challenge among the aging population.”

Frailty and sleep

Frailty can lead to low quality of life, illness and even premature death, according to the researchers. Additionally, older adults commonly develop sleep problems like reduced sleep duration and lower-quality sleep. This may create a dangerous positive feedback loop where sleep problems contribute to frailty and discomfort contributes to sleep problems, according to the researchers.

The researchers used Indian data from the second wave of the World Health Organization’s Study of Global Aging and Adult Health. In India, the study collected data from a nationally representative sample of people over the age of 50 across six Indian states.

In the current study, the researchers classified each of the 6,512 individuals in their sample as robust, pre-frail or frail using five variables: handgrip strength, walking speed, level of physical activity, level of fatigue and weight loss. The researchers created a frailty score for each individual based on their responses or performance. The researchers compared this measure of frailty with participants’ self-reported sleep quality, sleep duration and demographic measures including age, sex, education, marital status, work status and household wealth.

“Aging can disrupt deep sleep, increase nighttime awakenings and decrease total sleep overall,” Thalil said. “In our study, a quarter of the people over 50 were classified as frail, and nearly two-thirds were classified as pre-frail. While people cannot immediately change their frailty status, they can improve their sleep quality and delay or prevent becoming frail. Therefore, the relationship between frailty and sleep matters to the millions of older adults in India and nearly two billion older adults around the world.”

Different contexts, different results

Study participants who self-reported low-quality sleep were almost three times more likely to be frail than people who reported better sleep. This association indicates that sleeping well is critical to overall health, the researchers said, but the sleep duration results were more nuanced.

“Getting either too little or too much sleep has been associated with frailty in other studies,” Thalil said. “But our results showed that men who got nine or more hours of sleep per night — above the recommended seven to eight hours of sleep — were less likely to be frail than those who met the recommended amount of sleep. Women in the study followed the expected pattern of being less frail when they got the recommended amount.”

Because the relationship between frailty and the length of sleep for Indian men in this study differed from other studies of aging populations, the researchers said that it is critical to understand the specific relationships between sleep and frailty in different nations around the world.

“Context matters,” Lee said. “Just because the relationship between frailty and sleep works one way in the United States or other countries, that does not mean it will work the same way in India. When my collaborators and I conducted similar analyses on data from Taiwan, we saw very different results than we see in India. Researchers need data collected from the same people over time in India to understand the full implications of these results.”

Protecting and improving sleep for older adults

Despite differences across cultures, the researchers agreed that action is needed in every country.

“Frailty is a risk factor for dying earlier, and our findings reinforced our knowledge that sleep is significantly associated with frailty,” Lee said. “Older people need to focus on getting enough and high-quality sleep.”

Lee said the study has implications for medical practitioners as well.

"Medical providers need to ask older adults about their sleep patterns,” she said. “Everyone becomes weaker as they age, but if doctors and nurses can detect poor sleep and intervene, we may reduce frailty, a risk factor for morbidity and mortality for older adults. This could improve the quality of life for older adults and their caregivers everywhere.”

Manacy Pai of Kent State University and Bittu Mandal of the Indian Institute of Technology, Indore, contributed to the research.

The National Institutes of Health supported the researchers who conducted this study.