Not sure whether this is a sleep or feeding issue. My 5 month-old is waking roughly every 2 hours for a bf. For the first 3 months he could easily go 3/4 hours and he fed well in the day. Recently he spends hardly any time on the boob in the day. Instead he seems to be stocking up at night. Can't be sure how much he's taking in, but when he has expressed milk it's usually less than 4 fl oz. If I express after feeding there's loads of milk left. I give him a bottle of formula in the evening, but he rarely takes more than 4 fl oz, then wakes again a couple of hours later. He can go for 3 hours between feeds in the morning and evening, the more frequent feeding is just in the afternoon and night. He's a plump little boy in the 70th percentile for weight so no worries about weight gain.
Any tips on getting him to take decent feeds so he can go for longer - would be nice to get a bit more sleep!