These people are the ones that can drink coffee and go to sleep. Melatonin is a hormone produced by the pineal gland in the center of the brain. Melatonin helps the body establish healthy sleep patterns and influences energy and general health. Levels begin to decrease from the time we reach puberty. Others who can't find anything that helps them sleep may have emotional problems that they just can't or have chosen not to deal with.
Life is hard and everybody has their own set of challenges to deal with.
You may find some comfort on the wisdom area of the site. There are support groups and workbooks to help with emotional issues. In these situations, herbs will build the nervous system to handle life with a bit more ease, but stress does burn minerals, so you will have to take more than the average person. Often, we can eat foods that remove the minerals from our bodies. If you are taking or beginning to take minerals to sleep and want to get the quickest results, I would suggest you limit your intake of acid foods to give the minerals a chance to stay in your body and not be depleted due to an acid bloodstream.