baby sleep on top of heavy blanket?

so my baby is going through a sleep regression. every time I put him down he wakes up. no matter the position I put him in. however he stays asleep laying on my chest. today I put a heavy blanket under him in the bassinet and he’s been sleeping sound since. now every time I have put him down for his nap today I kept that heavy blanket underneath him and he’s slept so much better. I know the risk.. but I have been in the room with him the whole time. I’m just wondering if there is a safer alternative? He seems to be liking the comfort and snuggled feeling. help for the night please!!