The hormone melatonin (treating dementia).

The hormone melatonin, released by the pineal gland and considered important in regulating sleeping behaviour, has been cited as a beneficial supplement for patients with sleep disturbances.

Sleep disorders and disruptive nocturnal behaviour associated with dementia present a significant clinical problem. A characteristic pattern of sleep disturbance referred to as 'sundowning' has been described. This shows itself in increased arousal and activity, usually in the late afternoon, evening or night and is a cause of increased stress for carers.

There is considerable theoretical evidence to support the use of melatonin as a treatment for sleep disturbance associated with dementia. Melatonin is a hormone implicated in the control of the sleep-wake cycle. It is stimulated during darkness and suppressed by light. While the effects of melatonin have been extensively studied in animals, there is growing evidence that melatonin is also involved in the regulation and control of sleep and waking patterns in humans. Dementia appears to disturb these patterns.

One small but well conducted study evaluated the effect of bright light therapy in combination with melatonin or a placebo on restless behaviour. Bright light therapy was found to help restless behaviour, but the addition of melatonin negated the effect. Further research in the use of bright light therapy is necessary. A review found evidence to support the use of light therapy from four small studies, but again with calls for replication of the findings.