I would be very careful with the melatonin...although it is a common "natural" supplement, it may have side effects, and it has not been thoroughly tested (according to the FDA)...that may be why your government requires a prescription. I have written a little of my findings on the high/ low bp and sleep disorders boards but will include a synopsis here...
adverse reactions include the following: fatigue, dizziness, headache, irritability, and sleepiness, disorientation, confusion, sleepwalking, vivid dreams and nightmares, headache, difficulties with walking and balance, mood changes, psychotic symptoms, elevated blood sugar levels, elevated cholesterol levels, hormonal effects, increased breast size in men, decreased sperm count, decreased sperm mobility, nasau, vomiting, cramping,etc.
For your convenience, you can find a wealth of info at Medline Plus, the government's website on prescription drug, and nutritional supplements...:
I did my research on melatonin when I was posting regularly on the high/low blood pressure boards because some people there were touting melatonin as a means of reducing hypertension. When I researched there was some evidence that suggested melatonin may elevate blood pressure.
I'm curious to know if you monitored your blood pressure before you started taking this supplement and after you were taking this supplement, and if so, if you saw any differences in your pressures.
I live in the Netherlands and, unlike in the US, here you need a prescription to get melatonine. Does melatonine really work? I have terrible insomnia and it affects me at work.
It worked for me, but I took the very smallest amount and still had problems. I would sleep like a baby, but in the mornings I would have trouble breathing, and it felt like an a small anvil was on my chest. Wish I could've continued taking it because this was the ONLY thing that worked for my insomnia.
I have been on a continued dosage of melatonin for 4-5 years. Throughout that time period, I have monitored my blood pressure, allowing for variable factors (resting/active/etc). During this time, I have found no correlation between melatonin consumption and blood pressure. I am only one example though, so it is always wise to use caution.
Of the listed side effects, the only one that I have ever experienced is vivid dreaming, but I have had vivid dreams that I can recall as far back as 3 years of age. So, I do not think that the melatonin caused them, but it is known to intensify them in some patients. I should also note, that I do not doubt the other listed side effects, as different medications will react differently with different patients.
Where I live, melatonin is over the counter. I have never had any problems with side effects, ever, up to 15mg.
Melatonin is actually naturally produced by your body. According to what I've researched and read, it is produced as the sun begins to go down and your body prepares to sleep. Likewise, it is suppressed by bright sunlight, such as in the morning when a person (ought to) naturally wake up. This is why melatonin is often used together with light therapy. I've also heard of it being used in order to encourage the body's own natural production of melatonin.
As to whether the medical form works; personally, I've found that it creates a 'sleep gate' for sedatives to work in my body, but has never helped my sleep one bit on it's own. Then again, I am a special case. My doctors have treated many patients successfully with melatonin.
I've personally used from 4 to 12 mg's of melatonin and the effects varies for me. I haven't found much of a direct correlation between the melatonin or being able to sleep but I'm just one person, like you said. It did however make me tired if I recall correctly. I haven't taken it in years though. I still have the tablets, going to try taking it again and seeing if it has any different effects on me.