Using a pillow at 6 months???

[Pheebs24]

I've had an alarming discovery over the last week - my 6 mo baby sleeps more peacefully and for longer when he lies on my v-shape pillow in the cot, and I don't know what, if anything, I should do.

He's always preferred being slightly raised head-end and I've had a towel under his mattress for months, but now he's moving around it seemed a bit pointless as he'd end up with the raised bit under his back - so I removed it, and all was normal. Then one evening last week he was sounding like he had a lot of mucus and had been grumpy most of the day and I felt he would have a really uncomfortable night lying flat so I put him on this v-shape cushion we used to use when he was much younger and colicky.

He slept for 9 hrs!! He has never done more than 6 and even that was rare. The next night he did the same, so I put blocks under the head end of his cot and him back on the mattress thinking he just needed to have his top end raised again, and he woke every 4 hrs. Back on the cushion and 8 hrs. Off the cushion again and 4 hrs again.

So here I am. Obviously I want us both to get the best night possible, and I assume its a comfort thing as the cushion is not far off the length of his body, softer than the mattress and keeps him snuggled either side a bit like a cuddle. I'm concerned about how too many nights on the pillow would affect his back and spine development, but don't want to be an unnecessary martyr to sleepless nights - I'm tired enough already!

Should I try a baby pillow under the bottom sheet instead? Or just suck up the 4 hourly night feeds?