I use melatonin supplements on a fairly regular basis over the past year to regulate my sleep cycle, as recommended by my doctor to counteract Ritalin-induced insomnia. Studies have shown no reduction in efficacy after three months of use, according to Wikipedia[1]. If no change could be detected by that point, then there's a good chance that it's fine for extended use. From my own experience, this has held true.

[1] http://en.wikipedia.org/wiki/Melatonin#Stimulants

> My understanding is that taking it consistently isn't a good idea.

All the research I've read says that it makes absolutely no difference. You never develop an immunity to it and it doesn't inhibit natural production. No research (that I'm aware of) has yet to find a downside, even at regularly taken large doses.

Do you have a source? I haven't seen anything that suggests it isn't unhealthy. It take it almost daily, have done so for over six months, and have never slept better or had as much energy. It's also given me the energy to get in better physical shape.

I don't have sources that outline the issues on why taking it for a long time is bad. I have talked to a pharmacist and other articles stating that it's a temporary fix.

Here's another article mentioning that it should be taken for 3 months at most:

http://www.huffingtonpost.com/dr-michael-j-breus/melatonin-s...

The three months is because there have been studies showing it is safe for that long. But afaik there have been no studies suggesting that it would not be safe to take it for longer.

Gwern has a page (with a very pro-Melatonin message) with lots of links: http://www.gwern.net/Melatonin