Melatonin In Acute Mania Investigation (MIAMI-uk)

INTERVENTION: Melatonin (circadin) 2 mg tablet orally at night 1 hour 30 min before sleep, or placebo for 21 days. CONDITION: Bipolar disorder ; Mental and Behavioural Disorders ; Bipolar affective disorder PRIMARY OUTCOME: Young Mania Rating Scale at baseline, days 4, 7, 14 and 21. SECONDARY OUTCOME: 1. Activity on the Actiwatch to continue for 21 days; 2. Quick Inventory of depressive symptoms C16 (Clinician) at baseline, days 4, 7, 14 and 21; 3. Quick Inventory of depressive symptoms SR16 (self report) at baseline, days 4, 7, 14 and 21; 4. Altman mania rating scale at baseline, days 4, 7, 14 and 21; 5. Adverse events. Duration of follow‐up: 21 days; 6. Leeds Sleep Evaluation Questionnaire (LSEQ), carried out at baseline, day 4, day 7, day 14 and day 21 INCLUSION CRITERIA: 1. Age limit from 18 to 65, both genders 2. Young Mania Rating Scale >=20 3. In or out‐patients meeting the Diagnostic and Statistical Manual of Mental Disorders ‐ Fourth Edition (DSM4) criteria for bipolar disorder 4. Currently experiencing manic symptoms 5. Capacity to give informed consent