Yes, in my opinion l-tryptophan has much more "potent" sleep inducing properties than melatonin at any dose. Only the worst high-adrenaline / high-cortisol "wired" states cannot be subdued by it.
But not as effective as trazadone or Ambien.
A sufficient dose of L-tryptophan creates a significant, slightly psychoactive serotonin rush that feels warm and comfortable... inviting sleep come naturally. If I awaken in the middle of the night, an additional 1 - 1.5g of tryptophan will get me through till the first rays of morning sun.