
Put them to bed as normal, ensuring they have done everything they could possibly need to do (drinks, loo, teeth, cuddles etc). Then retire to chair on landing. As soon as they get out (of either bed or bedroom, depending on what your limitation is), you immediately go to them, and then the first time quietly but firmly "it's bedtime now. Goodnight" with nothing else said, and return them to their bed.
Back to chair to await second time up! This time just "It's bedtime now" and back to bed. Return to chair. On third and all subsequent occasions, say nothing at all, just return them to their bed.
The keys to making this work are apparently staying calm throughout, not talking at all, and keeping the patience to do it even if it takes 50 returns to bed on the first couple of nights. It's meant to improve things a lot within about 5 nights.
Personally I really struggled with the staying calm and patient bit - by about the tenth time out of bed I started losing my rag, so my 2yo ended up back in a cot instead




Shortcuts