Could melatonin be the cure for sleepless nights?
Bailey Heminger, PharmD, RPh, and Daniel J. Sheridan, MS, RPh, reply: Endogenous melatonin, a hormone synthesized and secreted by the pineal gland, helps to maintain a regular sleep–wake cycle.1 Nocturnal melatonin levels play an important role in both the initiation and maintenance of sleep.2
The rate of melatonin secretion varies with age and circadian rhythm. Nocturnal plasma melatonin levels are normally much higher than daytime concentrations because exposure to light suppresses the normal nocturnal increase in plasma melatonin levels. Levels also decrease as we age, resulting in age-associated insomnia.2
Patients may take OTC exogenous melatonin preparations for various reasons, including sleep problems related to jet lag, insomnia, and sleep–wake cycle disturbances.1,3 Advise your patients to talk with their healthcare provider or pharmacist before starting any OTC medication, including melatonin preparations, because they can interact with other medications and dietary supplements they're currently taking, including medications such as anticoagulants.1,4
Melatonin is considered to be a dietary supplement in the United States, so it's not regulated as a drug, and no prescription is needed.2 Inform patients that because the FDA doesn't approve or regulate the production or use of dietary supplements, they can't be sure the manufacturer is following safe and reliable manufacturing procedures.
The U.S. Pharmacopeia (USP) is a nonprofit scientific organization that creates standards for the quality and purity of dietary supplements as well as for medications and food ingredients. Advise patients to look for a USP endorsement when choosing a dietary supplement such as melatonin, but keep in mind that USP standards aren't enforced by any authority.
The effectiveness of melatonin isn't well established. Although it's considered to be safe when used for less than 3 months, it's recommended for use only for sleep disturbances that are due to delayed sleep–wake phase syndrome (a circadian sleep–wake rhythm disorder).5 Whether safe when used long term or in children isn't known.
Inform patients about the most common adverse reactions to melatonin, including daytime drowsiness, headache, and dizziness.4 Advise them that melatonin may have a safer adverse reaction profile compared with other sleep aids, including less risk of addiction and abuse.1
For insomnia, oral melatonin 3 to 4 hours before bedtime for up to 29 weeks has been used in most research.3,4 Patients, especially older adults, should begin with a low dose as directed by their healthcare provider and follow the manufacturer's labeled directions.
Finally, for nurses working alternating shift schedules, melatonin hasn't been shown to improve the time it takes to fall asleep, quality of sleep, or adjustment to rotating shift work. It may, however, slightly increase total sleep time.1,3
Women who are pregnant or are considering pregnancy shouldn't take melatonin without first having a discussion with their healthcare provider. Consult a pharmacist, the product label, or a current and comprehensive drug reference for more details on precautions, drug interactions, and adverse reactions. Remind patients to inform healthcare providers about all the drugs they use, including OTC medications and dietary supplements.