Nutrex Hibern8 Review


Hibern8 is a sleep-aid from Nutrex’s most recent line. It’s really nothing flashy, just the usual sleep-inducing/enhancing ingredients…


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Hibern8 is a sleep-aid from Nutrex’s most recent line. It’s really nothing flashy, just the usual sleep-inducing/enhancing ingredients…[Skip to the Bottom Line]


The relationship between Magnesium and sleep has been studied fairly extensively, and there appears to be a two-way correlation, with Magnesium helping to correct sleep-related issues in some studies, and inadequate sleep reducing Magnesium levels as well.

A 2002 study, published in “Pharmacopsychiatry”, found that Magnesium was able to increase slow-wave (deep) sleep and reduce Cortisol levels, thus normalizing age-related changes in sleeping patterns in elderly subjects. These results were replicated in a 2002 study from “Public Health Nutrition” in older (59 give or take 8 year old) subjects with inadequate dietary Magnesium intake.

Overall, while Magnesium may not be particularly effective in individuals with high (more than adequate) dietary intake, it can certainly improve sleep quality in those whose diets are lacking. Hibern8 contains about 50% of the RDI for Magnesium, a sufficient dose for normalizing any deficiency-related sleep issues.


GABA is the primary inhibitory (downer) neurotransmitter in the brain, as opposed to Glutamate which is the primary excitatory (upper) neurotransmitter. While increasing GABA levels in the brain certainly has an anxiolytic effect, supplemental GABA cannot effectively cross the blood-brain-barrier so supplementation with GABA itself isn’t really an effective way of increasing it in the brain. There are anecdotal reports of orally supplemented GABA inducing relaxation, but there are no studies confirming these reports.

Hibern8 contains 1000mg of GABA, a higher dose than we normally expect to see in sleep-aid supplements.


Tryptophan is an amino acid that, in addition to helping build proteins, acts as a precursor to 5-HTP (a direct precursor to Serotonin). Tryptophans potential as a sleep-aid has been known for quite some time, with most of the studies being performed 20-30 years ago. The results of most studies indicate that Tryptophan can increase drowsiness and decrease sleep-latency (time it takes to fall asleep). There are some reports of next-day grogginess, but this sort of subjective side-effect is highly variable and may impact some individuals but not others.

Hibern8 contains 500mg of Tryptophan per serving, a fairly sizeable dose that may very well help reduce sleep latency, perhaps adding the effects of Melatonin.


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 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. Effective doses range from .5-5mg with not much evidence to suggest efficacy is dose-dependent. That being said, Nutrex has opted for the high end of that range, and has included 5mg of Melatonin in the Hibern8 blend, helping to ensure that it will put you right you to sleep.


As a sleep-aid, Hibern8 is certainly effective, mostly due to the Tryptophan and Melatonin content. Though Nutrex doesn’t make any direct claims regarding muscle recovery and specific ingredients, the implication here is that deep, restful sleep enhances muscular recovery and helps to optimize growth potential. While this may be true, there is nothing particularly proprietary or innovative about Nutrex’s Hibern8 formula compared to other sleep-aid formulas we’ve reviewed.


[expand title=”REFERENCES” tag=”h5″]

  1. Takase, Bonpei, et al. “Effect of chronic stress and sleep deprivation on both flow‐mediated dilation in the brachial artery and the intracellular magnesium level in humans.” Clinical cardiology 27.4 (2004): 223-227.
  2. Sato-Mito, Natsuko, et al. “The midpoint of sleep is associated with dietary intake and dietary behavior among young Japanese women.” Sleep medicine12.3 (2011): 289-294.
  3. Held, Katja, et al. “Oral Mg< SUP> 2+ Supplementation Reverses Age-Related Neuroendocrine and Sleep EEG Changes in Humans.”Pharmacopsychiatry 35.04 (2002): 135-143.
  4. Murphy, Suzanne P., and Mary I. Poos. “Dietary reference intakes: summary of applications in dietary assessment.” Public Health Nutrition 5.6a (2002): 843-849.
  5. Nielsen, Forrest H., LuAnn K. Johnson, and Huawei Zeng. “Magnesium supplementation improves indicators of low magnesium status and inflammatory stress in adults older than 51 years with poor quality sleep*.” Magnesium Research 23.4 (2010): 158-168.
  6. Hartmann, Ernest. “Effects of L-tryptophan on sleepiness and on sleep.”Journal of psychiatric research 17.2 (1983): 107-113.
  7. Brown, C. C., N. J. Horrom, and Althea M. Wagman. “Effects of l-tryptophan on sleep onset insomniacs.” Waking & Sleeping (1979).
  8. Spinweber, Cheryl L. “L-Tryptophan administered to chronic sleep-onset insomniacs: Late-appearing reduction of sleep latency.” Psychopharmacology90.2 (1986): 151-155.
  9. Kunz, Dieter, et al. “Melatonin in patients with reduced REM sleep duration: two randomized controlled trials.” Journal of Clinical Endocrinology & Metabolism 89.1 (2004): 128-134.
  10. Brzezinski, Amnon, et al. “Effects of exogenous melatonin on sleep: a meta-analysis.” Sleep medicine reviews 9.1 (2005): 41-50.
  11. Cajochen, Christian, et al. “Melatonin and S-20098 increase REM sleep and wake-up propensity without modifying NREM sleep homeostasis.” American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 272.4 (1997): R1189-R1196.
  12. Ursin, Reidun. “Serotonin and sleep.” Sleep medicine reviews 6.1 (2002): 55-67.
  13. Powers, Michael E., et al. “Growth hormone isoform responses to GABA ingestion at rest and after exercise.” Medicine and science in sports and exercise 40.1 (2008): 104-110.

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