Ashwagandha, it really works. And ofc part of Buhner's protocol.
It lowers cortisol. There is a randomized double blind placebo controlled study for this, so you know it's effective:
www.ncbi.nlm.nih.gov/pubmed/23439798"The treatment group that was given the high-concentration full-spectrum Ashwagandha root extract exhibited a significant reduction (P<0.0001) in scores on all the stress-assessment scales on Day 60, relative to the placebo group. The serum cortisol levels were substantially reduced (P=0.0006) in the Ashwagandha group, relative to the placebo group. The adverse effects were mild in nature and were comparable in both the groups. No serious adverse events were reported."
I take 500mg at night (but in your case you should take during the day, too) and it helps me stay asleep the whole night. There is a cortisol spike around 2-3am, part of the sleep cycle, but if your initial cortisol levels are high to begin with, that spike will wake you up and you will not be able to fall back to sleep.