I've heard that babies can have a wakeful period at around four months, where a baby who's been sleeping fine all of a sudden starts waking during the night. Why does this happen, and how should I deal with it?

Yes, this is commonly known as the four-month sleep regression. The reason behind it is because your baby’s sleep “matured”. Newly born, the only reasons why your baby needs to be awake is when he/she is hungry, feels uncomfortable (e.g., soiled diaper) or he/she simply doesn’t feel a need to sleep anymore. Within the first three months, as your baby grows, the frequency for night feeds decreases and hence, he/she will sleep for longer periods throughout the night. However, as your baby reaches around three to four months old, their sleep matures. Your baby starts to go through the different sleep stages that form the sleep cycle (approximately 120mins per cycle). Waking after each cycle is a normal way for the baby to check that he/she is still safe. Once your baby starts going through the four-month sleep regression, you can start the process of sleep training to help your baby get used to the sleep cycles. In the meantime, here are some tips to help encourage your baby to sleep more: - help your baby gets back to sleep after waking by doing things that you have been doing (e.g., feeding, rocking, holding) - swaddle or offer a pacifier to help calm and encourage the baby to sleep - offer a dream feed to help your baby sleep a little longer - ask people around you to help put the baby back to sleep while you get some rest yourself Here is an article with a section that offers useful tips to help your baby adjust if your baby is about three-four months but has yet to show signs of sleep regression: https://childsleepscience.wordpress.com/2014/03/12/the-four-month-sleep-regression-what-is-it-and-what-can-be-done-about-it/ And here’s another with some great tips on how to help move past this period: http://www.babysleepsite.com/baby-sleep-patterns/4-month-sleep-regression/

Like Hui Qun mentioned, your baby is probably going through sleep regression. What I did was to lessen his activities an hour before his nap time, and to ensure he has at 3 naps during the day so that it's easier to get him to sleep. Also, I have a flask of warm water & canisters of measured milk powder so that I can make the milk as soon as possible if he wakes up for milk. I am a light sleeper and he co-sleeps with him, so I usually wake up at his slightest movements. By the time I'm done making his milk, I can dreamfeed him and *most* of the time, he continues sleeping. Otherwise, I let him sleep on me and that seems to help calm down a lot.

thanks