Simply, Melatonin is a hormone produced naturally from the pineal gland situated at in the back centre of your brain. It is pretty much the size and shape of a pine nut - hence pineal. It it believed to govern and repair some of the body's other glands. Some people produce more and some less than 'average' but over time and as we age, the gland might calcify, and produce less melatonin. The stuff that is mostly available is synthetic, produced in a laboratory from natural products and is certainly safe in that there are no animal contaminants. It has been found to help with sleep and jet lag but many other benefits are claimed.
Whilst I fully appreciate and value lovinglife's research, I think it puts it more in perspective when considering that in my own research, it has not been easy to find contraindications. I have told my diabetic nurse(s) and consultant(s) that I sometimes use Melatonin and received no objection. I think perhaps lovelife's findings are more illuminated when read with the whole paragraph relating to side effects on page 5 of the site:
"Endocrine (blood sugar elevations): Elevated blood sugar levels (hyperglycemia) have been reported in patients with type 1 diabetes (insulin-dependent diabetes) and low doses of melatonin have reduced glucose tolerance and insulin sensitivity. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a healthcare provider, and medication adjustments may be necessary."
Catherincherub's advice about always checking the contraindications is right, of course. I have indeed done this with the product that I use from a well known manufacturer. There are contraindications given for those using tranquilisers, with an autoimmune conditions, with depressive disorders and pregnant/lactating women.
There is no reference to diabetes but Type 1 Diabetes is an autoimmune disease and concurs with lovinglife's findings. I choose to believe, because of my BS levels and personal control, that Type 2 isn't an autoimmune disease and does not affect me. This is my personal consideration and I keep an eye on it. I think that if anyone has any doubts - "just say no".
Personally, I only ever take (ocassionally) less than half a gram (I nibble a tiny amount off the tablet) because more makes me feel groggy in the morning. Someone recommended 2 x 3mg which I think would be a lot to start with. It is considered that the maximum daily safe amount is 6mg. A common side effect that I also get is enhanced REM sleep. REM means Rapid Eye Movement and mostly occurs near to waking, when we dream. For me, this type of sleep can be very deep and quite delicious. I sometimes dream more vividly.
Good luck all,
Russ