A babys sleep cycle is actually only 45 mins, and adults is 1.5 hours - but helping them 'join' sleep cycles together is the key

My DD is just 4 months, she was having 4 or 5 x 45 min sleeps a day for a while, drove me a bit nuts, as with a toddler its easier if she had a long nap. However she's started linking 2-3 sleep cycles together now so I am getting 2 big sleeps and 1 shorter one each day now. I didn't actually do much to encourage it, she just started doing it. If she does wake after a short time I will either cuddle her, pop the dummy in, pat her or sometimes even give her a bit of boob if she's rooting for it to get her to continue to sleep.