Night sleep

Je

My 5 month old sleeps anywhere from 12-15 hours at night and doesn’t not sleep during the day. Is this normal? He’s been doing it for months. I’ve tried waking him up earlier to try and get him to nap but he won’t! I’ve tried every tips and tricks from others and doctors to get him down for naps but he still will cry the entire time and never gives any sleepy cues. Not sure how to get him to nap.