By Lilian Anekwe
Melatonin is safe and effective long-term treatment for insomnia in older patients, according to a UK-led randomised controlled trial.
Prolonged-release melatonin (PRM) is licensed in the UK for the short-term treatment of insomnia in patients aged 55 and older, but data on the long-term efficacy and safety of the treatment has been lacking.
In a double-cross parallel group trial, researchers from the University of Glasgow treated 791 adult patients with poor quality sleep and difficulty falling asleep with PRM or placebo and found the intervention group had a 'clinically relevant' improvement in sleep latency with no increase in adverse effects.
All patients had a run-in period of placebo for two weeks, and then were randomised patients to either PRM or placebo each night for three weeks. Patients who completed the course of placebo were then also randomised to either PRM or placebo for a further 26 weeks.
The researchers also measured patients' endogenous melatonin levels, to establish if age or low melatonin excretion is a better predictor of response to PRM.
After three weeks patients aged 65-80 showed a significant improvement in sleep latency – the length of time patients took to fall asleep – falling asleep an average of 15.6 minutes sooner than patients on placebo.
Over a longer term, sleep latency throughout the six-month period was significantly shorter in the PRM group, with a mean difference of 14.5 minutes compared to patients on placebo.
Questionnaire responses also showed PRM treatment was associated with a significant improvement in sleep maintenance, quality of sleep and morning alertness up to three months, before reaching plateau levels that were maintained for the rest of the six month period.
Adverse events were mild, with no clinically relevant differences between PRM and placebo for any safety outcome.
Professor Ian Ford, director of the Robertson Centre for Biostatistics at the University of Glasgow concluded: ‘The PRM efficacy reported is not only statistically significant but also clinically relevant.
'Furthermore, there were no signs of tolerance, as there was no reduction in benefit during long term treatment. A low melatonin level, regardless of age, is not useful in predicting response to PRM in insomnia. Thus clinicians do not require melatonin measurement prior to treatment.'
BMC Medicine 2010, 8:51
Melatonin is licensed for short treatment periods in the over 55s
