Zinc as a Sleep Aid
Zinc as a Sleep Aid
I have addressed the problem of Sleep Disorders in an older blog, and expanded on that material to create a more comprehensive overview for a chapter found in Health Secrets for the 21st Century: Volume Two.
However, given the increasing frequency of sleep disorders among the general population, any new material that may be of help deserves to be explored. So, in this newsletter I will be examining the role of zinc in sleep.
Zinc, the second most abundant trace mineral in the body, is an essential mineral required for many biological processes. Now, new evidence strongly supports the idea that zinc is also involved in the regulation of sleep. Recent research has discovered that “zinc serum concentration varies with the amount of sleep, while orally administered zinc increases the amount and the quality of sleep in mice and humans”.
Over 300 enzymes in the body require zinc to fulfill their functions in areas which include digestion, metabolism, immunity, skin health, protein production, and DNA synthesis. (Source)
As scientific inquiry began to realize that zinc also had a role to play in the central nervous system (CNS), recognizing its importance in memory and neurotransmission, researchers eventually turned to examining the role of zinc in sleep. However, as of yet, “the mechanisms by which zinc regulates sleep remain unclear, rapid progress towards their elucidation is to be anticipated.” (Source)
Studies on zinc and sleep began with mouse studies, primarily this one: Zinc-containing yeast extract promotes non-rapid eye movement sleep in mice. Rapid eye movement (REM) occurs during the dream state, but non-rapid eye movement occurs during deep sleep, when we fully rest and restore. Zinc is found, among other places, in the brain, where it has the “potential to interact with and modulate many different synaptic targets, including glutamate and GABA receptors”. Glutamate (which is an excitatory neurotransmitter) and GABA (which is inhibitory) play central roles in brain activity, so zinc is clearly a nutrient that has potential to impact wakefulness, and sleep states.
This mouse study found that “zinc-containing yeast extract dose dependently increased the total amount of non-rapid eye movement sleep and decreased the locomotor activity”. However, the zinc “preparation did not change the amount of rapid eye movement (REM) sleep or show any adverse effects such as rebound of insomnia during a period of 24 h following the induction of sleep. This is the first evidence that zinc can induce sleep.”
There is actually an advantage to not increasing REM (dreaming) sleep, for as I mentioned before, we do not rest and restore while dreaming. For some people supplements like kava kava and melatonin cause excessive dreaming, and thus leave susceptible people unrested when they use these products.
After finding confirmation of the sleep potential of zinc among animals, researchers next turned to humans. The purpose of the following study, “was to examine the effect of zinc-rich and astaxanthin-containing food on sleep in humans”.
Now, this study added astaxanthin, an antioxidant found in seafood such as salmon and krill, due to its potential to “chelate minerals and promote zinc absorption, which in return may also improve sleep”. Astaxanthin, a reddish carotenoid, is a unique cell membrane nutrient with many clinical benefits, along with anti-aging properties. (For more on the subject of astaxanthin follow this link.)
Krill is a particularly good source of astaxanthin because krill oil occurs in a phospholipid form, as opposed to other fish oils, which are in a triglyceride form. This means that (like liposomal products) this form of marine oil has the ability to easily enter into cell membranes, and to cross the blood brain barrier. (Thus, krill oil has been found to be effective in treatment of adult ADHD.)
Those nutrients that can cross the blood brain barrier (something I’ve discussed in previous blogs) are of particular value when attempting to influence neurotransmitter functions, in this case those involved in sleeping. And the ability of astaxanthin to “chelate minerals”, means that the zinc will be bound to the astaxanthin, which can then serve to transport it directly into the brain. Clearly of benefit in this case.
This particular study, randomized, double-blinded, and placebo-controlled, included 120 healthy subjects, who had their night activity recorded for 12 weeks. Here are the results: “These subjects were divided into four groups: placebo, zinc-rich food, zinc and astaxanthin-rich food, and placebo supplemented with zinc-enriched yeast and astaxanthin oil. Compared with the placebo group, the zinc-rich food group efficiently decreased the time necessary to fall asleep and improved sleep efficiency, whereas the group that ingested zinc-enriched yeast and astaxanthin oil significantly improved the sleep onset latency.” (Sleep onset latency is the amount of time it takes you to go from being fully awake to sleeping.) (Study)
So, while eating zinc-rich foods was helpful, the greatest benefit came from those who were supplemented with zinc-enriched yeast and astaxanthin oil. This suggests that one will find more effectiveness with using zinc and astaxanthin supplements, than food alone.
Further Support for Zinc
A population study (2009) done on 890 healthy Chinese subjects, evaluated the relationship between “zinc/copper serum concentrations and several physiological factors such as sex, age, drinking and smoking behavior, and sleep”.
In this study, “the mean concentration of serum copper remained constant regardless of the amount of sleep; however, the highest concentration of serum zinc was found in subjects sleeping a “normal” amount of 7 to 9 h per night, compared to short (<7 h) and long (>9 h) sleepers”.
Another Chinese population study “compared blood zinc concentration and sleep quality in 1295 children from the Jintan Child Cohort. Blood sampling was performed on the same children twice: at preschool (3–5 years old) and several years later during their 6th grade (11–15 years old). No significant association between zinc status and sleep could be found in these children in their younger age; however, blood zinc concentration correlated with sleep duration and sleep quality in their pre-adolescent age. Furthermore, a longitudinal association between the first and second sampling periods demonstrated that zinc blood concentration at preschool age predicted the development of poor sleep quality and efficiency several years later.”
How Much Zinc?
An obvert zinc deficiency will manifest as a loss of smell and taste, white spots on the fingernails, or poor wound-healing. But, we may have suboptimal zinc levels without showing any major symptoms.
While the RDA for zinc is 8 – 9 mg/day for adults in Canada, and 15 mg/day in the U.S., the amount believed to be ideal in the natural healing field is somewhat higher. This amount can vary depending on who we are getting information from, but generally it is believed that women should ingest 10 to 15 mg daily, and men from 20 to 30 mg daily (more if suffering from prostate problems). As usual, I suggest skipping weekends when supplementing with non-water soluble nutrients, like zinc, to ensure that, if we have ingested too much, the body has a chance to use up the excess.
That being said, zinc will use copper in its assimilation, so ideally when taking a zinc supplement one should ensure some copper is present. NutriStart has two products containing adequate zinc, along with copper. These are the NutriPods and Mineral Mix, both of which offer 15 mg of zinc per serving. For men, who have higher zinc requirements than women I would suggest the NutriPods for Men (containing 20 mg zinc), or for those using Mineral Mix to take 3 or 4 caps per day, rather than the two caps recommended for basic needs.
If one is to try experimenting with increasing their zinc intake in order to help with sleeping, it certainly seems to be a good idea to add some krill oil, as a source of astaxanthin, since the combination seemed to have an even more powerful effect than zinc alone. (NutriKrill)
Alternatively, one can also purchase a pure astaxanthin product, derived from algae. However, Dave Asprey, author of the Bulletproof books and blogs, points out that higher blood levels of the omega 3 fatty acid DHA have been linked to better sleep (Study), and in other studies “oily fish consumption is associated with better sleep quality.” (The “oily” fish are those highest in omega 3 fatty acids, and include herring, mackerel, salmon, sardine, and trout.)
Asprey also states that: “I’ve found that krill oil gives me the best sleep. I’ve experimented with various kinds of fish oil, and pretty much every other omega-3 supplement you can think of, and only krill oil has made a noticeable impact. I recommend consuming your fish or krill oil at least two hours before bedtime.” (Source)