This is going to sound insane... but I have seizures and out of all the illegal drugs I've done, I have to say when I was first prescribed them... anticonvulsants were some of the best highs I ever had. You have the mellow of mot, the skin sensitivity of rolling on some of the best x ever, the bright colors and occasional hallucinations of shrooms, and the not give a fuck attitude of alcohol. Without all the bad side effects of any of them. IVs of them are especially fun because it just hits you all at once.
But I know exactly what you're talking about with the Nyquil. :3 Sometimes I force myself to stay up past the point of actually being sleepy just to revel in that numbness.