Zinc is another well researched mineral for sleep.
Zinc, melatonin, and magnesium were evaluated in a research study by Rondanelli et al. in 2011 on individuals with insomnia. While melatonin may have aided falling asleep, they believed that magnesium and zinc contributed to the restorative benefits of sleep.
Zinc is important for the metabolism of melatonin (cofactor alert). It has a calming impact on the nervous system and is also known to aid in mental recuperation following stress.
Fixing a zinc deficiency will also aid men in optimizing their testosterone. One study examined the effects of a zinc and magnesium supplement. It showed that men who consumed 30 mg of zinc daily had higher levels of free testosterone than those who didn't. Another trial put a group of elderly men who had a slight zinc deficiency on zinc supplements for six months. As a result, their serum testosterone levels had increased significantly after 24 weeks.