A sleep disorder exists when you have a lower quality of sleep that results in impaired functioning or abnormal sleepiness. Melatonin and Ambien CR are substances used to promote sleep. Your body naturally produces melatonin, and you can also purchase a synthesized version of the substance. Ambien CR, on the other hand is a purely synthetic substance.

Melatonin

Melatonin is a hormone. The pineal gland is the part of the brain that makes melatonin. Melatonin may help your body determine when it should go to sleep and when it should wake up. Melatonin is, therefore, considered a substance that can modulate your body’s circadian rhythms. Melatonin levels in the body are typically low during the day, but increase during sleep. According to the Mayo Clinic, melatonin supplements are often used to treat sleep problems. Examples of sleep problems include jet lag, shift-work disorder, insomnia, and delayed sleep phase disorder.

Ambien CR

Ambien CR is the commercial name of the drug zolpidem. The CR stands for continuous-release. The Food and Drug Administration approved Ambien CR for the treatment of insomnia. According to the prescribing information, unlike benzodiazepines, Ambien CR is more selective, has a shorter half-life and is less addictive. Typical side effects of the drug include headaches and next-day fatigue and dizziness. Neither pregnant nor breast-feeding women or children should use Ambien CR.

Zolpidem and Melatonin in Daytime Sleep

It is possible that combining melatonin with low doses of zolpidem might take advantage of the unique properties of both. Namely, promoting healthy sleep without enhancing impairments seen with high-dose zolpidem. A study reported in the December 2008 "Human Psychopharmacology" found no somnogenic benefits from combining melatonin 5 mg with low doses of zolpidem (5 and 10 mg). Thus, melatonin 5 mg appears to have some advantages over zolpidem 20 mg in terms of post-sleep performance effects. The study specifically examined reaction times and memory recall in patients the day following intake of zolpidem and melatonin.

Zolpidem and Melatonin Interaction

A study reported in the December 2008 "Human Psychopharmacology" also found that the combined use of melatonin and nonbenzodiazepine hypnotics such as zolpidem may result in the enhancement of sedation and impairment of memory, coordination, and attention. The study further found that a prolonged-release form of melatonin didn’t impair performances on any cognitive tasks. On the contrary, zolpidem significantly impaired psychomotor and driving performance at one hour and four hours post-dosing. These impairments were exacerbated by combining the Ambien CR with melatonin.