Z-Slim PM Review

Z-Slim PM is a sleep-aid by MusclePharm (Fit Miss) designed to encourage weight-loss while at rest. As a sleep-aid, it’s pretty effective but, like most night-time weight-loss supplements, the weight-loss aspect is iffy…

Z-Slim PM



Valerian is widely used, both as an herbal supplement and tea, to promote relaxation and reduce anxiety. Valerenic acid, a primarily bioactive component of Valerian, has been shown (in vitro and in mice) to bind to GABA receptors in the brain, potentiating their signaling. This would explain the subjective reports of reduced anxiety following oral supplementation, though a 2002 study from “Phytotherapy Research” failed to show any such benefit in humans with generalized anxiety disorder.

Because Valerian is relatively popular as an herbal anxiolytic, it is also alleged to influence sleep (quality and latency). A 1985 pilot study found that 450mg Valerian extract decreased sleep latency (time it takes to fall asleep). However, a 2010 meta-analysis which compared 10 qualified studies found insufficient evidence to support these findings. The same meta-analysis also determined that there was insufficient evidence to support the claims that Valerian can enhance sleep quality.

Overall, the evidence is not overwhelmingly in favor of Valerian as a sleep-aid, but the anecdotal evidence, combined with a couple positive studies, indicates that there may be something to it. We wouldn’t consider a game changer in the context of the Z-Slim PM formula, but it may play a role afterall.


Lemon Balm: Lemon Balm has long been used in traditional medicine as a relaxation/sleep aid and is alleged to improve quality of sleep. There is also preliminary evidence to suggest Lemon Balm may attenuate certain stressors, but further research is needed before conclusions can be drawn. Studies regarding the potential sleep enhancing effects of Lemon Balm tend to include Valerian as well, making it difficult to determine the efficacy of just Lemon Balm alone. Ultimately, it does appear that Lemon Balm, especially when combined with Valerian (as in the Z-Slim PM formula), may (slightly) improve sleep quality.


5-HTP is the direct precursor to the “happy” neurotransmitter Serotonin, which plays a vital role in sleep. Though the relationship between 5-HTP supplementation and sleep quality remains under-researched, a 2010 study found that a combination of 5-HTP and GABA was able to enhance sleep quality in humans. Unfortunately, this study was confounded with the inclusion of other ingredients which may have altered the results.

That being said, there is a litany of subjective, anecdotal reports of 5-HTP improving sleep quality as well as duration and latency (time it takes to fall asleep). While we wouldn’t regard these reports as facts, they certainly lend credibility to the already established notion that 5-HTP may improve certain aspects of sleep. The Z-Slim PM formula contains an undisclosed amount of 5-HTP, but average doses range from 50-200mg.


Raspberry Ketone, a molecular constituent of Raspberries, has become extremely popular for its alleged fat-burning properties. A 2005 in vitro study, published in “Life Sciences”, found that Raspberry Ketone was able to augment (enhance) Noradrenaline-induced lipolysis, meaning it could theoretically potentiate the effects of other fat-burners. However, the concentration of Raspberry Ketone used in this study would not be practical for oral consumption in humans.

Only one human study involving Raspberry Ketone has produced positive results with regards to weight-loss, but this particular study combined Raspberry Ketone with Caffeine, Synephrine, and Capsaicin, so the weight-loss observed cannot be attributed to Raspberry Ketone at all. As stated above, the amount of Raspberry Ketone needed to convey any sort of fat-burning effect in humans is too high to make oral consumption practical. Unfortunately, Raspberry Ketone is just one of those buzz ingredients that keeps finding its way into weight-loss products, despite no positive human studies.


Melatonin is a hormone secreted by the pineal gland, found in the brain. It is heavily involved in the sleep-wake cycle (by causing drowsiness when secreted). Due to its role in promoting sleep, supplemental melatonin has been used to correct and treat mild sleep disorders, as well as by people who experience mild sleeplessness. All evidence suggests that melatonin works very well when it comes to promoting sleep, but the quality of sleep is more difficult to record.

A 2004 study, published in the Journal of Clinical Endocrinology & Metabolism, found that melatonin significantly increased REM sleep in subjects who suffer from lower than normal REM sleep durations. Several other studies have demonstrated the ability of melatonin to increase REM sleep duration, as well as decrease sleep latency (time to fall asleep).

Overall, melatonin may be very useful as a sleep aid, and may increase REM sleep especially in those experiencing REM deprivation to some extent. Although the exact amount present in the Z-Slim PM formula is unknown, the dose doesn’t really matter much with Melanin. .5mg conveys more or less the same benefit as 5mg.


As a sleep-aid, Z-Slim PM may be moderately effective because it does contains a few ingredients shown to enhance sleep quality as well as sleep latency. However, as a weight-loss agent, the formula falls short. Raspberry Ketone is the only ingredient that is even alleged to burn fat and, as mentioned above, it doesn’t live up to the hype. Contrary to the name, Z-Slim PM is not an effective night-time weight-loss supplement. That being said, MusclePharm positions it more as a sleep aid which “may support nighttime metabolism”, so they aren’t really claiming it’ll burn fat (just implying it). At around 50 cents per serving, Z-Slim PM is a little on the expensive side for sleep-aids, and roughly the same benefit could be derived from a combination of 5-HTP and melatonin for significantly less.

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