Question about Dexedrine dosing

[firahs75]

At about 2pm I took 30mg Dexedrine IR and felt really really nice. However, I have not been able to get to sleep. If I take another 30mg 18 hours or so after the original dose, without having slept, will I get that loving feeling again or will it be a waste?

Also, would taking dexies diminish an MDMA high if taken the day before the MDMA?

THanks!