The joy of a cheeky daytime power nap is not to be underestimated - but it seems it could come at a cost.
Lovers of long snoozes during the day are putting themselves at risk of type 2 diabetes, according to a new study,
Scientists from the University of Tokyo established the link after looking at data from 21 observational studies, involving more than 300,000 people.
They found that those who bedded down for an hour or more during the day have a 45 per cent higher risk of developing the condition.
The study is being presented at a meeting of the European Association for the Study of Diabetes in Munich.
Naveed Sattar, professor of metabolic medicine at the University of Glasgow, agreed that there was considerable evidence linking sleep disturbances and diabetes.
He said: “It’s likely that risk factors which lead to diabetes also cause napping. This could include slightly high sugar levels, meaning napping may be an early warning sign of diabetes.
"What we need are trials to determine if, when and for how long one sleeps makes a difference to real health outcomes.
"Trials bring truth and without proper trials, we simply will never know the answer.”
Shorter naps of less than 40 minutes have no known link to diabetes, meaning nap fans needn’t ditch their short sleeps altogether - but they may prefer to set an alarm from now on.
Dr Benjamin Cairns, from the cancer epidemiology unit at the University of Oxford, said the findings should be treated with caution.
He said: “In general, it is not possible to make conclusions about cause and effect based on observational studies alone, because usually they cannot rule out alternative explanations for their findings.”