This was a good little review of nutrients that affect sleep. After reading it I’m thinking vegetarians might not be the best sleepers.
The Relationship Between Micronutrient Status And Sleep Patterns: A Systematic Review, Public Health Nutrition, March 2017
The following nutrients are all thought to improve sleep, in one way or another:
The association between Fe and sleep duration has been consistently reported in infants and the general adult population.
[They cited numerous examples, in both infants and adults, with either iron-deficiency anemia or not.]
The randomized controlled trials, using maternal reports of sleep patterns, found longer night-time and total sleep duration in infants who received supplemental Zn than in the placebo group. This finding agrees with an observational study that found an association between decreased Zn and very short sleep in a general adult population. In terms of nutritional biomarkers, researchers found that shorter sleep duration or increased odds of sleep insufficiency were associated with lower serum Zn levels in women and children in early adolescence.
The involvement of Mg in sleep patterns has been investigated in infants and older adults.
[They cited numerous examples of magnesium’s effect on sleep, including the one I posted about here.]
The results showed mixed effects of vitamin B12 on sleep patterns.
[I posted numerous studies that support a link between B12 and sleep at Having Trouble Sleeping? Vitamin B12 May Help. What I learned from that was, “B12 doesn’t by itself aid sleep, it’s B12’s effect on melatonin that aids sleep. And melatonin, in turn, is affected by light and dark. The two together (B12 plus light early/dark late) have a profound effect on sleep.” Since there are other variables in B12’s effect, you can see why it would show “mixed results” in studies. Also, anecdotally, people who take B12 report increased energy during the day, which may interfere with the ability to fall asleep or stay asleep.]
Some other points they made:
1. There is some evidence that copper and vitamin D also affect sleep, but it’s not as clear-cut as iron, zinc, and magnesium (and possibly vitamin B12).
2. They note that taking too little or too much of a nutrient may both be a problem: “Optimal rather than high or low micronutrient levels are essential for healthy sleep.”
3. Finally, and this one is key: “Sleep effect may change depending on the level of another micronutrient, suggesting an interaction among micronutrients.”
For example, although Fe and Zn supplements alone reduced the length of naps as well as increased the duration of night-time sleep and total sleep in infants, infants receiving Fe together with Zn supplements did not exhibit such sleep effect.
So, there are possible antagonistic effects between and among vitamins … one may promote sleep, one may inhibit sleep, and together they may cancel any sleep effect.
Nonetheless… iron, zinc, magnesium, and vitamin B12 are nutrients that are often linked to healthy sleep. And of the 4, 3 (iron, zinc, B12) are nutrients that vegans are usually low in. That’s not to say omnivores are never low in them but iron, zinc and B12 are either found in higher amounts in animal foods or are better absorbed from animal foods. For example, the RDA for iron for a premenopausal woman is 18 mg. A 1/2 cup serving of kidney beans, which is a good source of iron, has just 2 mg, and that 2 mg is less bioavailable than 2 mg of heme iron in meat.