anxiety and stress
"There is a lot of other reviews that I have read that sums a lot of it up. Yes, you will most likely experience yawning, nausea, and headaches at first. It does go away! At first I also noticed a change in my sex life. I could still get in the mood but found it near impossible to orgasm. 
Also, with sleep, I did feel tired for a bit, but I think it was because I experienced trouble sleeping at first.
I found some things that helped fix some of this:
I went from 20mg to 10mg a day.
I took it right after breakfast.
This one is important! Exercise! I started running again and I found that it had an extremely positive effect and it went well with the medication. A lot of the jitters I got at first went away, it helped me sleep better, and more!"