DDAH2 and insomnia: By comparing normal rats with insomnia rats treated with LSPC B2 for seven days through gastric lavage, they observed several positive changes in the treated rats: reduced walking time and forelimb lifting frequency; decreased levels of norepinephrine, glutamic acid, ADMA, sleep latency, and 8-iso-prostaglandin in the brain; and, concurrently, prolonged sleep duration, increased concentrations of 5-hydroxytryptamine, nitric oxide, and gamma-aminobutyric acid in the brain as well as the upregulated expression of DDAH1, DDAH2, and neuronal nitric oxide synthase.