Melatonin in mood disorders

World J Biol Psychiatry. 2006;7(3):138-51.

Melatonin in mood disorders.

Srinivasan V, Smits M, Spence W, Lowe AD, Kayumov L, Pandi-Perumal SR, Parry B, Cardinali DP. Department of Physiology, School of Medical Sciences, University Sains Malaysia, Kubang Kerian, Kota Bharu, Kelantan, Malaysia.

The cyclic nature of depressive illness, the diurnal variations in its symptomatology and the existence of disturbed sleep-wake and core body temperature rhythms, all suggest that dysfunction of the circadian time keeping system may underlie the pathophysiology of depression. As a rhythm-regulating factor, the study of melatonin in various depressive illnesses has gained attention. Melatonin can be both a 'state marker' and a 'trait marker' of mood disorders. Measurement of melatonin either in saliva or plasma, or of its main metabolite 6-sulfatoxymelatonin in urine, have documented significant alterations in melatonin secretion in depressive patients during the acute phase of illness. Not only the levels but also the timing of melatonin secretion is altered in bipolar affective disorder and in patients with seasonal affective disorder (SAD). A phase delay of melatonin secretion takes place in SAD, as well as changes in the onset, duration and offset of melatonin secretion. Bright light treatment, that suppresses melatonin production, is effective in treating bipolar affective disorder and SAD, winter type. This review discusses the role of melatonin in the pathophysiology of bipolar disorder and SAD.

PMID: 16861139 [PubMed - in process]

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written by Mood Disorders, October 14, 2010

The treatment of choice for most SAD patients is bright light exposure, which causes phase advances when scheduled in the morning. Because patients know when they are exposed to bright light, however, there is a considerable placebo response associated with it. Melatonin can also cause phase advances, but it has to be taken in the afternoon. The Lewy team used afternoon melatonin to test if it was more antidepressant than melatonin taken in the morning, which causes phase delays. The researchers randomly assigned 68 SAD patients to one of three treatment groups, taking placebo capsules or melatonin in the morning or afternoon for three weeks. After four years of study, they concluded that, similar to persistent jet lag, circadian misalignment is a major part of SAD. Most patients, typically phase-delayed types or night owls, have misalignment that responded best to taking low-dose melatonin in the afternoon or evening. A longer-than-expected subgroup of SAD patients, phase-advanced types or morning larks, responded best to taking low-dose melatonin in the morning. Melatonin did not cause drowsiness, because the doses used were lower than what is usually taken at bedtime. In addition to bright light exposure, another treatment may be in the offing once low-dose, sustained-release melatonin formulations become available. However, people in the phase-advanced subgroup should use these treatments at different times of the day than the typically phase-delayed type of patient.
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