Researchers have found that frequent napping is associated with an elevated prevalence of type 2 diabetes and impaired fasting glucose in an older Chinese population.
Results of the study show that the prevalence of type 2 diabetes was 36% higher (adjusted odds ratio = 1.36) in participants who reported napping four to six times a week and 28% higher (OR = 1.28) in those who napped daily. Similar associations were found between napping and impaired fasting glucose. The observed associations were unaltered in statistical analyses that removed participants with potential ill health and daytime sleepiness, suggesting it is less likely that diabetes leads to daytime sleepiness and raising the possibility that napping may increase the risk of diabetes.
According to the authors, napping in China is a social norm, which is practiced by all ages primarily as a habit started in childhood. In Western countries, napping is less common and is often unplanned and prompted by sleepiness likely caused by aging, deteriorating health status, or nighttime complaints.
Lead author Neil Thomas, PhD, reader in epidemiology at the University of Birmingham, UK, said that additional research is needed to determine if napping itself plays a causative role in the development of type 2 diabetes, or if other factors are involved.
"In many non-Mediterranean, Western countries a large proportion of those that nap are generally older or have other conditions that cause tiredness and create an urge to nap," said Thomas. "The napping can therefore be a marker of disease."
The study was published in the March 1 edition of the journal SLEEP.