Catnapping

How do I stop it?!

For the first 3.5 months I used to wrap him, quick cuddle and putting him to bed awake. He would then just go off to sleep, and was in a 3 hourly sleep-feed-play routine. But in the last few weeks, Harry started catnapping during the day - wakes up after 45min and cries. He is obviously tired but can't seem to get himself off to sleep, and nothing I do helps except rocking him in the buggy.

It's beginning to affect his night sleeps as well.

As we have stopped wrapping him, I wonder if that was a sleep association that is now gone...? What else can I use?