NOW Foods Glycine Pure PowdervsNatrol Advanced Sleep Melatonin 10 mg (Time Release)

Glycine is both a building-block amino acid and an inhibitory neurotransmitter in the central nervous system. Taken before bed, research suggests it promotes peripheral vasodilation that lowers core body temperature - a physiological signal closely tied to sleep onset - and acts on NMDA receptors in the suprachiasmatic nucleus, the brain's master clock. The net effect in studies was faster sleep onset and improved sleep quality without altering overall sleep architecture.

Melatonin is the hormone your pineal gland releases as darkness falls to tell the brain it is time to sleep. Supplementing it binds the same MT1 and MT2 receptors, which can advance or initiate the sleep phase. Natrol's two-layer tablet releases part of the dose quickly to help with sleep onset and the rest gradually to support staying asleep, and adds vitamin B6, a cofactor in the body's own melatonin synthesis.

The headline evidence is a 2007 study by Yamadera and colleagues in which 3 g of glycine before bed improved subjective sleep quality and shortened the time to fall asleep and to reach slow-wave sleep on polysomnography in people with unsatisfactory sleep; it also reduced daytime sleepiness and improved a memory task. Follow-up work from the same group reported reduced fatigue and better next-day performance after sleep restriction. The caveat is that these trials are small and largely from a single research program, so the evidence, while encouraging, is far from definitive.

Melatonin's evidence is strongest for circadian problems such as jet lag and delayed sleep phase, where it can meaningfully shift sleep timing. For falling asleep faster in general, meta-analyses show a real but small benefit, often cutting sleep latency by only several minutes. The AASM gives melatonin a weak recommendation against use for chronic insomnia, citing limited efficacy and safety data. Higher doses like 10 mg are not proven more effective than lower ones and raise the chance of side effects.

Glycine is exceptionally well tolerated because it is an amino acid the body already uses in large amounts; the most that sensitive users tend to report is mild stomach upset or soft stools at high intakes. As with any supplement, start at the studied dose rather than exceeding it. This is educational information, not medical advice; individual results vary.

The most common complaints are next-morning grogginess, headache, and vivid dreams, all more likely at this 10 mg strength. Melatonin can interact with several medication classes. Because supplemental melatonin is not tightly regulated, independent testing has found products whose actual content differs from the label, so brand reputation matters. This is educational information, not medical advice; individual results vary.

At about $29.99 list (and frequently under $25 at third-party retailers) for a 1 lb tub, and a studied dose of roughly 3 g, you get on the order of 150 bedtime servings - pennies per night. That makes glycine one of the lowest-cost ways to run a personal sleep experiment.

At roughly $8-$12 for 60 tablets as of 2026, this is one of the lowest cost-per-night sleep aids on the market - typically well under 20 cents a dose. It is widely HSA/FSA eligible. The real cost is not money but the high dose: most users do not need 10 mg.

Generally healthy adults curious about a low-risk sleep-quality aid. People who are pregnant or nursing, or who have a serious medical condition or take prescription medication, should consult a clinician first. It is not intended to treat diagnosed insomnia or any sleep disorder.

Adults dealing with jet lag, shift-work sleep disruption, or occasional sleeplessness. Not recommended for children without pediatric guidance, for pregnant or nursing people, or for those on blood thinners, sedatives, immunosuppressants, or blood-pressure medication without checking with a clinician. Avoid driving or operating machinery until you know how it affects you.