I don't have any studies to back it up, but I know someone who used to take it every day and she said it's harder for her to fall asleep without it than it used

I don't have any studies to back it up, but I know someone who used to take it every day and she said it's harder for her to fall asleep without it than it used to before she started taking it. Naturally our body adjusts to anything that we ingest.