Your tolerance goes right back down if you stop taking it for a couple weeks.
When I met my wife she was giving the kids melatonin every night, and had been for months. She wondered why it wasn't helping them. I explained why, so we now only give it to them every once in a while. It was obnoxious to stop though because the boy got really anxious when we stopped, which had the effect of keeping him up. I explained the placebo effect to him but it took a while for him to figure out that he doesn't need a pill to sleep. They both sleep much better now that they live with me. /story time
When I met my wife she was giving the kids melatonin every night, and had been for months. She wondered why it wasn't helping them. I explained why, so we now only give it to them every once in a while. It was obnoxious to stop though because the boy got really anxious when we stopped, which had the effect of keeping him up. I explained the placebo effect to him but it took a while for him to figure out that he doesn't need a pill to sleep. They both sleep much better now that they live with me. /story time