Although the causes of Hypersomnia are not clear yet, scientists are currently studying the roles of various neurotransmitters (specifically hypocretin/orexin, dopamine, histamine, serotonin and gamma-aminobutyric acid) in the brain and spinal cord. Genetic ties are also being currently studied as family history is present in up to 39% of people with idiopathic hypersomnia. The impact of the genes associated with the circadian rhythm are also being studied (genes that may be different for those that have idiopathic hypersomnia).