4 hour afternoon naps ?

[BigSur]

My 6 week old has started going down around 2 or 3 pm this week and will sleep deeply for three / four hours (maybe longer if I let him?). It's a problem because he never sleeps that long or well at night.  We've been putting him down around 8 pm for the night and he'll sleep for 2 -3 hours, wake for a feed and go back to sleep. But then from 2 am on, he's awake part of each hour until his wake up time around 7 am.

I'm wondering if he has his days / nights switched or partially so and if there's a way to move that long afternoon nap closer to bedtime so that he sleeps longer in the night.  Should I wake him?  He naps about 3 other times in the morning and midday but only 40 - 60 minutes usually.  Any help would be great.

[Samuel's mum]

I personally would say to wake him as you don't want to encourage a day/night switch as you say. You want calories/feeds to continue in the daytime and encourage any massive blocks of sleep to be in the night. So I would wake him in order that he can continue to feed 'on routine'.
When you do wake him try and look for a window when he seems in a lighter phase of sleep e.g. some movement, eye movement, breathing changes. It will hopefully make it easier to wake him and encourage him to feed.