Sleep deprivation is insane - is this normal?

My son is 3 weeks old and I don't think I've slept more than 2 hours at a time in like 2 weeks straight. Wife and I are just trading off nights but even when it's supposedly my turn to sleep I can't because I'm listening to every sound he makes. Every cry has me jolting awake thinking something's wrong. She keeps telling me to relax but how do you relax when you're responsible for a tiny human? Does this get better?