I'm sure this has been done before but I was hoping for some of your wisdom on the subject.
DS1 is 2.10 and DS2 is 3 weeks old. It's come as a shock because DS1 has always been easy going, co-operative and well behaved. Now he is defiant, cheeky and often seems to be looking for the next opportunity to be naughty. He's also started waking in the night (normally only once and easily settled but on top of DS2 keeping us up it's pretty annoying) and has regressed with his toilet training when he was doing so well.
As far as I'm aware this is a textbook reaction to a new baby but I'm interested to know how others have dealt with it?
We have no 'naughty step/chair' or structured discipline as frankly we've never needed it but I'm wary of introducing something now on top of everything else going on in his life. So far we've been trying to ignore the bad behaviour and reward the good but our patience levels and tiredness means it not working well and we end up shouting 
Thanks in advance!