Need advice please...?

Well today I did a pretty stupid thing...I had a major test in college today, and normally I wouldn't do this, but I took 400 mg of vyvanse as a performance enhancer (I know, I know...very stupid idea), I have another test tomorrow, and I can't go to sleep now...so I took 125 mg benadryl to try to help me sleep, and it hasn't helped one bit. So this is what id like to know, Is there any way I could fall asleep on my own? If not, and I pull an all nighter, will lexapro help alleviate some of the withdrawal symptoms of the vyvanse? (btw I'm prescribed both vyvanse & lexapro...so I'm not doin anything illegal) and please don't answer if your don't have any good advice for me.