A Monash University-led collaborative study investigated the ways diet contributed to the relationship between sleep quality and mortality among elderly men and women.
Women who ate a varied diet, including sources rich in vitamin B6, could still live long lives despite poor sleep habits, according to the study that had researchers from Monash University, National Defence Medical Centre, Taiwan, and National Health Research Institutes, Taiwan.
Mark Wahlqvist, Emeritus professor at Monash University, said sleep played a more important role in men's mortality than women's.
"Poor sleep has been associated with increased morbidity and mortality, including obesity, diabetes, cardiovascular disease and coronary heart disease.
"We found that for both genders, poor sleep was strongly correlated with poor appetite and poor perceived health," Walhqvist said.
He said there was significant interaction between sleep quality and dietary diversity. For men, poor sleep was not associated with a greater risk of death unless there was also insufficient dietary diversity. For women, good sleep only provide a survival advantage if they had a diverse diet.
The study, recently published in the Journal of the American College of Nutrition, found women were almost twice as likely as men to sleep badly.
Women who were poor sleepers had a lower intake of vitamin B6 from food than those whose sleep was rated fair or good. Also, fair sleepers had lower iron intakes than good sleepers.
However, both men and women could improve their outlook by eating a more varied diet.
"Sufficient dietary diversity in men could offset the adverse effect on mortality of poor sleep while women need to make sure they are eating foods high in vitamin B6," he said.
People who did not sleep well were also less able to chew, had poor appetites and indulged in less physical activity. These characteristics could contribute to lower overall dietary quality and food and nutrient intake, especially for vegetables, protein-rich foods, and vitamin B-6, Walhqvist said.
"They may also contribute to the risk of death, either in their own right or together with problematic sleep. Intervention focusing on education on healthy dietary practices in elderly people could improve sleep duration and provide more stable levels of health," he said.