Melatonin production decreases with advancing age, leading to insomnia and changes in circadian rhythmicity. Administration of melatonin in variable doses resulting in supraphysio- logical or physiological night-time blood levels of melatonin has been shown to improve sleep quality in the elderly. To study the effect of low doses of melatonin, which do not affect daytime blood melatonin concentrations, night-time milk containing 10