However, the new study has suggested that this may be a side effect of the hormone's primary job as a stress-buster.
For the study, researchers manipulated ghrelin levels in mice through a variety of methods, including prolonged calorie restriction, ghrelin injection and a genetic modification rendering the mice numb to ghrelin's effect.
They found that mice that had limited ghrelin activity seemed depressed. If pushed into deep water they made no effort to swim and when introduced to a maze, they clung to the entryway. Also, when placed with other mice, they did not socialize.
On contrary, mice with high levels of ghrelin swam energetically in deep water, looking for escape. They eagerly explored new environments and were much more social.
Researchers said that elevated ghrelin could be why some people overeat when under pressure.
The study has suggested that if the stress-induced snack is avoided, ghrelin levels will remain high and help us confront the stressor in a calm, effective way.
The study is published in the July 2008 issue of the journal Nature Neuroscience.