How to keep from falling asleep after...

Whenever I finish it makes me feel like I took a double dose of nyquil, I just can't keep my eyes open! It extremely difficult for me to stay awake even a few minutes. Kind of a problem when you have a sweet BF who like to get you off before the "main event". I know this is pretty common in men but I also notice they will wake up given proper motivation that doesn't seem to work for me though. Does this happen to other women and how do you wake up? Guys if you have some advice I wouldnt mind hearing that too! Thanks!