Can potty training interfere with sleep?

[InsaneDame]

After nearly 2 years of awful sleep my ds2 finally started sleeping through at 22mo but after 3 months of wonderful sleep it's all gone wrong again. First it was the warmer nights unsettling him - he was up twice a night for a drink. A good night would be once, a bad night 3 times. I started potty training a couple of days ago - not going amazingly but the worst thing is he was up 4 times last night and in between times he was shouting out in his sleep. Is this a developmental thing? Should I try to 'do' something? When he wakes it's normally for a quick drink or tuck in then back off to sleep. He is still in a cot, self settles at bedtime, sleeps 8.30/9pm until 7.15ish (I often have to wake him) and has a nap 12.45pm until 2pm. He was so tired today after the disturbed night, I struggled to keep him awake on the school run.

He is 26mo by the way.