My DS has just started sitting up independantly - it's lovely to watch him play during the day with this new found ability

but ...the downside is that he wakes himself up at night, several times.

It started two nights ago, every couple of hours pretty much. THis evening he went down happily as 7:15pm, then woke up 1.5 hours later crying and sitting up. Since then he's woken up about 8 times ( in the last hour). DH and I have taken turns going in and doing pat/shush. I find that he just needs repositioning and will go back to sleep within minutes. I don't say anything and I find that just my presence seems to begin to calm him. But I'm dreading this continuing through out the night. What's the best way of dealing with this? I've got him in a sleeping bag, and I stopped swaddling him at 5 months (he's now 8 months). Should I be doing something in the day to teach him how to lie down? Or if there is nothing I can do, can anyone advise on how long this may take to pass? I'm only half way through the BW for Toddlers but can't seem to find anything specifically on this (I don't seem to have much time to read these days!)
Thanks for your help.
zeena