The natural cortisol hormone cycle is that cortisol should be high in the morning and low at night.  Sometimes people can not sleep because their cortisol is too high at night (either they are simply too stressed out or for other reasons.)

The supplement Sleep Tonight! by Enzymatic Therapy contain blends of ashwagandha (an adaptogenic herb that helps lower cortisol and balance thyroid hormones [reference]) and L-Theanine as well as other ingredients.  Theanine is derived from tea leaves.

This product Sleep Tonight is mentioned in Jacob Teitelbaum’s article Tips for a Great Night’s Sleep. He is the author of the book From Fatigued to Fantastic.

Certain supplements are not suitable for certain people and/or conditions. Check with your medical professional first.