If you find your child will only sleep for 40 minutes when he/she should be having a 2 hour nap then you need to listen to your child when she awakes. Is your child crying? If she isn’t then leave her be, she may well return to sleep. If she is fussing a lot, go to her and try patting/rubbing/shushing her back to sleep. Do this for the period until it is the time you want her to get up. For short nappers it is very important that their nap times are pretty much the same time every day so that their body clock can develop. You need to be patient with this and continue doing this until your baby learns to sleep longer.
If your child is awakening too early for you, (the normal wakening time would be between 6 & 7) you need to look at the naps. However, if your child is up at 5am then your child will not last until 9am for their next nap so you will need to put your child for a nap earlier. You should try and hold off on the nap until about 8ish if you can and let your child sleep a bit longer (max 20mins longer). This will have a knock on effect to the lunchtime nap so you may have to put her to bed 15 minutes earlier at lunch then try and keep to the rest of your routine as normal. Also if your child starts wakening at 5am only give enough of a feed to get her through to 7am and give the rest then. If you start giving a full feed at 5am her body will start to expect it and then it will become the norm.
Once you have your child in a routine that works for you then be very happy with yourself. However, do remember that things do change and you do need to tweak the routine frequently to keep up with your child’s developments.
When babies reach developmental milestones it often affect’s sleep. One very common issue is when your child starts to crawl or move about on their own around 8/9 months they can suffer from separation anxiety and may begin to wake during the night. Normally they just want reassurance that you are there and everything is ok. Be careful how you handle this, always reassure your child but be careful not to start any negative sleep associations such as staying with them until they fall off to sleep, giving a bottle or bringing him to your bed. This is normally just a phase that you have to grin and bear for maybe 2/3 weeks and then he will move on.