Urinary 6-Sulphatoxymelatonin levels are depressed in chronic migraine and several comorbidities - Masruha, Marcelo R.; Lin, Jaime; Vieira, Domingos S. de Souza; Minett, Thais S. C.; Cipolla-Neto, José; Zukerman, Eliova; Vilanova, Luiz C. P.; Peres, Mario F. P. (Headache, 2010)