Melatonin also occurs naturally in such foods as rice and bananas. Consequently, it can be sold as a dietary supplement in the United States without premarket approval from the U.S. Food and Drug Administration. Clinical studies of melatonin have been few, but gradually more are being funded. The National Institute on Aging, for example, is funding the Alzheimer's Disease Cooperative Study of melatonin for sleep problems in AD patients. Because of the AD patient's sleeping difficulties, many families finally decide to place their loved ones in nursing homes.
Prior research indicates that melatonin decreases with advanced age.
In one recent study, Liu et al. The investigators found the CSF melatonin levels in AD patients were only one-fifth of those in control subjects. Such an investigation is being carried out by the Alzheimer's Disease Cooperative Study. Physicians can refer their patients, or families can self-refer to the medical centers participating in the melatonin protocol, said Pay. The University of California, San Diego is one such center.