​London, May 10 (IANS) Decisions are best taken when you are full. Researchers have found that the hormone ghrelin -- that is released before meals and is known to increase the appetite -- has a negative effect on both decision making and impulse control.

"For the first time, we have been able to show that increasing ghrelin levels that are seen prior to meals or during fasting, causes the brain to act impulsively and also affects the ability to make rational decisions," said one of the researchers Karolina Skibicka from Sahlgrenska Academy, University of Gothenburg in Sweden.

When hungry, the hormone ghrelin is produced in the stomach. In the new study conducted on rats, the hormone has been shown to have a negative effect on decision making capabilities and impulse control.

The rats can be trained to be rewarded (with sugar) when they execute an action such as pressing a lever ("go") -- or instead they can be rewarded only when they resist pressing the lever ("no-go") when an appropriate signal is given. 

They learn this by repeatedly being given a signal, for example, a flash of light or a buzzing sound that tells them which action should be executed for them to receive their reward.

An inability to resist pressing the lever, when the "no-go" signal is given, is a sign of impulsivity. 

Researchers found that rats given ghrelin directly into the brain, which mimics how the stomach would notify us of a need to eat, were more likely to press the lever instead of waiting, despite it causing them lose their reward.

Higher levels of ghrelin prevented the rats from being able to wait for the greater reward, said the study published in the journal Neuropsychopharmacology.​