First of all, stress doesn't necessarily cause increased output of cortisol. Anxiety attacks do, but that's an intense thing. PS won't help with cortisol. If it does anything, it improves overall brain function. Cortisol is sent to the adrenal gland from a part of the primitive brain called the amygdyla, so the control of it comes by controlling the adrenal gland so it works in a more balanced fashion. If anxiety is the cause of it, though, if you don't control the anxiety somehow, it will keep happening, but you can lessen the symptoms by reducing cortisol output. Again, if it's just sleep problems, it might not be cortisol related at all, the brain is a complicated thing and we can be very anxious or have terrible insomnia without producing a whole lot more cortisol. You know when it's really shooting out because that's what causes the classic fight or flight reaction, which when it happens without rational cause and frequently causes panic attacks in those of us who get them. There are herbs called adaptogens that help calm the adrenals. Ashwagandha is very widely used, and the best I've found for cortisol is holy basil, but I'm not sure these will help you if you take them at bedtime as the adrenal gland also gives you energy and a balanced one can keep you calm and also energize you at the same time, so you'd usually take these during your day, not at bedtime. But I really don't think the sleep thing is a cortisol reaction as much as a problem with how you're thinking and the stress you're causing yourself at bedtime assuming it's not something physiological, such as a thyroid problem or other imbalance or nutritional deficiency. Also, don't meditate any time close to going to bed -- if you're meditating well, it can give you a lot of energy -- it's a lot like the effect of a good nap. So don't meditate too close to the time you go to sleep. You might not be tired. I personally have taken PS for a long time but it's prophylactic because I take medication, and I'm trying to protect my brain function from the dangers of taking medication. It won't do what you're looking for. Something called melatonin, about 1mg, might do the trick, as might something like a homeopathic remedy called Calms Forte, but the best cure is to cure your anxiety problem -- I know, not easily done. I've never done it. But I hope you do.
Neuro PS works great in many ways...I switched to it instead of antidepressant meds that had horrible side affects and I was able to reap the befits of increased memory focus and brain function... which is really important since dementia runs in my family.