5 weeks old and sleep?!

Desiree

FTM of a 5 week old baby girl, and she has been sleeping really well. Last night she slept for 8 hours before waking up to eat... should I let her sleep like that again or wake her to eat? My MIL said to never let her go more than 4 hours without eating but my mom said never wake a sleeping baby! So I need advice lol thanks in advance!