Nabilone Versus Amitriptyline in Improving Quality of Sleep in Patients With Fibromyalgia

Inclusion Criteria: * Patients aged ≥18 years; * A diagnosis of fibromyalgia according to the American College of Rheumatology classification criteria (Wolfe F, Smythe HA, et al 1990); * Suffering from self-reported disturbed sleep; * Negative urine screen for cannabinoids; * Women of childbearing potential must agree to use adequate contraception during study and for 3 months after study; * Ability to attend research centre every second week for approximately seven to nine weeks and be able to be contacted by telephone during the study period; * Stable drug regimen for 1 month prior to randomization; * Normal liver (AST \<3x normal) and renal function (serum creatinine \<133µmol/L); * Haematocrit \>38%; * Negative serum bHCG; * Proficient in English or French; * Willing and able to give written informed consent; * Ability to follow study protocol (cognitive and situational). Exclusion Criteria: * Patients currently using cannabis or cannabinoid or tricyclic antidepressants (TCA) and who are unable to undergo a 2 week washout period before entering the study; * Pain due to cancer; * Unstable cardiac disease such as cardiac arrhythmias, cardiac failure, ischaemic heart disease and/or hypertension on clinical history and examination; * History of psychotic disorder or schizophrenia; * Known hypersensitivity to cannabinoids, amitriptyline, or related tricyclic antidepressants; * Currently taking or unable to stop taking monoamine oxidase inhibitors (a two-week washout period is necessary for subjects taking MAOIs); * History of seizures/epilepsy; * Diagnosis of glaucoma; * Urinary retention; * Pregnancy and/or breast-feeding; * Participation in other clinical trial in the 30 days prior to randomization; * A recent manic episode (within the past year); * Current suicidal ideation or history of suicide attempts