M.F.
I know there are differing opinions about this...but in my experience with two breastfed children, 4 1/2 months is too young to expect to not be breastfed AT LEAST once sometime in the night. I would expect that if has been 5-6 hours since he last ate, I would feed him, especially if he is having a harder time going back to sleep. Also, when babies go through growth spurts during different times in their lives, they breastfeed more often, so keep that in mind as well. I'm thinking that somewhere around 7 or 8 months and my little ones were eating solid foods was when they could sleep throughout the night...but, this also seemed to come and go...I think they go through cycles or sleeping better and then waking in the night depending on growth, teething, illness, hunger, etc. So trust your instincts on what your baby is wanting/needing when he wakes and I believe you'll figure it out! Good luck! I know how good a solid nights sleep feels when you haven't had one for months! :)