One RCT in 120 patients with schizophrenia on antipsychotics reported that ramelteon 8 mg as add-on medication significantly increased the night-time melatonin, serum arylalkylamine N-acetyltransferase (AANAT), and urinary 6MTas levels as compared to only antipsychotics without the add-on ramelteon [95]. This evidence concerns the gene AANAT and schizophrenia.