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The rice advice for sleep


16 February 2007

Hgh glycemic index rice may boost tryptophan and serotonin, two brain chemicals involved in sleep, Dr Chow said
Hgh glycemic index rice may boost tryptophan and serotonin, two brain chemicals involved in sleep, Dr Chow said

A meal of starchy rice four hours before bedtime may solve your insomnia problems, new research from the University of Sydney has found.

The University of Sydney's Dr Chin Moi Chow and colleagues found that carbohydrates that quickly raise blood sugar (those with a high glycemic index) may hasten sleep.

The researchers studied 12 healthy men, 18-35 years old, who had no sleep problems. Over three nights at the researchers' sleep lab they fasted for five hours before being served a meal.

The meal of rice with steamed vegetables in tomato puree varied only in the type of rice and serving time.

"Two of the meals included jasmine rice and were served one hour before bedtime and four hours before bedtime respectively," said Dr Chow. "The third meal, which included a type of long-grain rice that was low in glycemic index, was also served four hours before bedtime."

Dr Chow and her colleagues altered the type of rice used in order to measure the effects of carbs with high and low glycemic indices. "Jasmine rice has a high glycemic index, while the long-grain rice we used in this study has a lower glycemic index," Dr Chow said.

Dr Chow's team changed the timing of the meal to see what impact that would have on sleeptime. The men were free to go to bed whenever they wanted; the researchers timed how long it took the men to fall asleep once in bed.

Eating the jasmine rice meal four hours before bedtime proved to be the best way to hasten sleep: the men fell asleep after nine minutes, on average, that night. It took nearly 15 minutes, on average, to fall asleep after eating the jasmine rice meal one hour before bedtime.

The men were slowest to fall asleep after eating the long-grain rice meal four hours before bedtime - taking nearly 18 minutes, on average, to fall asleep. The study, recently published in The American Journal of Clinical Nutrition*, found the meals had no other observable effect on the men's sleep.

Dr Chow's team doesn't know exactly how carbs with a high glycemic index affect sleep. "These kinds of foods may boost tryptophan and serotonin, two brain chemicals involved in sleep", Dr Chow said. Adding protein to the meal might change the results, she added.

Dr Chow and her team plan to carry out further studies this year. "We are fine-tuning the meal contents and meal sizes so they are suitable for everybody, including diabetics, whilst still helping people to fall asleep."

* Afaghi, A., O'Connor H, Chow CM. The American Journal of Clinical Nutrition, February 2007; Vol. 85: pp. 426-430.


Contact: Kath Kenny

Phone: 02 9351 2261 or 0434 606 100