DD started sleeping 8-12 hours straight most nights after she started using walking as her main means of getting around. She started walking a week before her 1st birthday but it wasn't until about 13.5-14 months that it became her main means of moving around. She sleeps from about 7:30am until 6:30am most nights and sometimes wakes me up at about 3am but she's not usually fully awake at that time...I just change her nappy and give her a bottle. She'll only generally wake in the middle of the night if she's wet through, although some mornings when she's slept right through I go in and change her and she's almost saturated.