Quoting Boobie On Demand:" He's been like this for a few days too. And its not just him waking up more often, its a struggle to ... [snip!] ... aware he's on our bed. It sucks,especially because he was sleeping about 7 hour stretches. He's 3.5 months, how about yours?"
There is something they call the 4 months sleep regression - that could be part of it AND milestones (like rolling over) disturb sleep. Are you still swaddling? I found that helped even at this age. In fact I think we went back
to it at about 4 months.