Anybody else's newborn sleep for long periods of time? He is 8 days old eats for about 30-45 minutes…

Anybody else's newborn sleep for long periods of time? He is 8 days old eats for about 30-45 minutes and then sleeps around 5 hours. He pees and poops regularly and is very content, so I know he's got to be getting plenty to eat. But he's going over 5 hours now of sleeping and I feel like it's time to wake him up to feed. This just started the day before yesterday, I'm thinking since my milk came in he's just getting full and not needing to eat as often.