(Ivanhoe Newswire) -- Frequent napping is associated with an elevated
prevalence of type 2 diabetes and impaired fasting glucose in an older Chinese
population.
A recent study shows that the prevalence of type 2 diabetes was 36 percent
higher in participants who reported napping four to six times a week and 28
percent higher in those who napped daily. Similar associations were found
between napping and impaired fasting glucose. The observed associations
suggested that it is less likely that diabetes leads to daytime sleepiness,
raising the possibility that napping may increase the risk of diabetes.
"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," lead author Neil Thomas, PhD, reader in epidemiology at the
University of Birmingham, U.K., was quoted as saying. "The napping can therefore
be a marker of disease."
The community-based study took place in Guangzhou, China, where 19,567
participants between the ages of 50 and 93 years were recruited from 2003 to
2004 and 2005 to 2006.
Participants underwent a half-day assessment, which included a structured
interview on lifestyle and medical history, and a physical examination.
Self-reported frequency of napping was obtained by questionnaire, and type 2
diabetes was assessed by a fasting blood glucose sample and/or self-reports of
physician diagnosis or treatment.
Type 2 diabetes was identified in 13.5 percent of the sample and was more
prevalent in people who reported napping daily and in those who napped four to
six times per week. At least one nap per week was reported by 67.2 percent of
participants, more commonly in males than in females. About 60 percent of these
people reported napping daily.
In a sub-sample of 3,822 participants who were re-contacted for additional
information about sleep habits, there was a statistically significant trend of
increasing diabetes risk with longer nap duration. Compared with people who
never took naps, the risk of diabetes was 41 percent higher for people who took
naps that lasted longer than 30 minutes and 35 percent higher for people whose
naps lasted 30 minutes or less.
The authors noted that the association between napping and diabetes was observed
despite the fact that nappers had higher levels of physical activity, which has
been shown to reduce the risk of diabetes. This suggests that the relationship
between napping and diabetes might have been stronger had it not been offset by
the protective effects of physical activity. The authors added that there will
be profound public health implications in China if the relationship between
napping and increased risk of type 2 diabetes is confirmed in longitudinal
studies, as the nation is currently affected by an emerging diabetes epidemic.
SOURCE: SLEEP, March 1, 2010
