Maybe for counteract this effect we can try this, looks promising:
http://www.ergo-log.com/withaniasomnifera.html
a little part extracted: "In the infertile men with normal sperm, the herb increased testosterone production by fifteen percent. In the men with a low sperm count we're talking about an increase of forty percent, and in men with slow moving sperm an increase of 21 percent."
The study calculated an average of 40 % increase, but what is more important to us, is the cortisol reducing and sleep-aid effect:
http://www.anabolicmen.com/ashwagandha-testosterone/
"Since ashwagandha is an adaptogen, it should reduce stress, anxiety, and balance stress hormones (mainly cortisol). To my surprise, ashwagandha is actually well-proven to do all of those, while also improving subjective well-being. Take this well-done double-blind placebo study for example, where 300mg’s of KSM-66 ashwagandha given to human subjects for 60 days, was able to slash cortisol levels by 27%, while also greatly reducing anxiety and mental-stress in the test subjects. Another study with KSM-66 noted 14% reductions in cortisol, while in one study which used 5g of the root powder, up to 32% reductions in cortisol were noted in subject males who suffered from stress-related infertility. Multiple animal studies have come to same conclusions: ashwagandha supplementation consistently reduces cortisol levels and improves many stress-related symptoms."
I know it's a little off topic, so sorry, but this herb can help if the TA cause sleep problems. Definitely a good add-on to the Eurycoma i think!