The best evidence for efficacy is in sleep onset
insomnia and
delayed sleep phase syndrome. It is most effective when administered 3-5 h before physiological dim light
melatonin onset. There is no evidence that extended-release
melatonin confers advantage over immediate release. Many children with developmental disorders, such as
autism spectrum disorder,
attention-deficit/hyperactivity disorder and
intellectual disability have sleep disturbance and can benefit from
melatonin treatment.
Melatonin decreases sleep onset latency and increases total sleep time but does not decrease night awakenings. Decreased
CYP 1A2 activity, genetically determined or from concomitant medication, can slow metabolism, with loss of variation in
melatonin level and loss of effect. Decreasing the dose can remedy this. Animal work and limited human data suggest that
melatonin does not exacerbate
seizures and might decrease them.
Melatonin has been used successfully in treating
headache. Animal work has confirmed a
neuroprotective effect of
melatonin, suggesting a role in minimising neuronal damage from birth
asphyxia; results from human studies are awaited.
Melatonin can also be of value in the performance of sleep EEGs and as sedation for brainstem auditory evoked potential assessments. No serious adverse effects of
melatonin in humans have been identified.