Australian researchers are looking for the perfect meal to send you to sleep.
Work is underway at the University of Sydney to better understand how foods ranking high on the glycemic index (GI) help people doze off.
A study involving ten healthy sleepers has shown those fed a high GI diet would fall asleep about nine minutes sooner than those on a low GI diet.
Christopher Herrera says while the research holds promise for those who have trouble sleeping, caution is also needed to ensure what is good for sleep is not bad for the waistline.
"When we talk about high GI foods, we do have to be careful that people are not overloading with sugary foods or cookies or that sort of thing," Mr Herrera, a PhD candidate and post graduate fellow at the university, told AAP.
"We don't want the public to believe they need to overload in high GI foods or overload in carbohydrates (to improve their sleep)".
High GI foods include white bread and pasta or white rice but also sweets like jelly beans.
Nutritionists discourage a diet laden with high GI foods because of their link to obesity and diabetes.
When it comes to sleep however, Mr Herrera says these foods have been shown to boost the brain's intake of the amino acid tryptophan.
Tryptophan is the precursor to the hormone serotonin, which is known to calm anxiety and also lead to sleep.
Mr Herrera said tests have shown how tryptophan levels peak in the body about three hours after a high GI meal.
"So have your last meal three hours before your usual bed time," he said.
"What we're saying is choose a high GI carb for dinner - so a white rice versus a brown rice or two pieces of white toast rather than brown toast.
"We think that will increase the availability of this tryptophan to the brain, which will help you fall asleep."
The research has also gone some way to confirming an "old wives tail", Mr Herrera said, that a glass of milk before bed improves sleepiness.
He said milk had a "very high content of tryptophan" along with turkey, cheese, nuts and spinach.
Although, he says, it was the increased sugar load of high GI foods that prompted the brain to readily take it up.
"I do feel that the public is becoming more aware of sleep so these types of things are important," Mr Herrera also said.
"... there are strong links between poor sleep and increased mortality, also increased cardiovascular disease."
Mr Herrera presents the results of his research at the Australasian Sleep Association Conference, under way in Melbourne this week.
