In 2000, researchers at the UCLA Center for Sleep Research published findings showing that people with narcolepsy had 90 percent fewer neurons hypocretin in their brains than healthy people.
Later, the same group demonstrated that hypocretin is an arousing chemical that keeps us awake and that the death of hypocretin cells helps explain the sleepiness of narcolepsy.
But it has remained unclear what kills these cells.
Now the same UCLA team reports that an excess of another brain cell type - this one containing histamine - may be the cause of the loss of hypocretin cells in human narcoleptics.
If such, this can be a breakthrough towards finding a cure to narcolepsy.