My son does the same thing! I always thought it was just a quirk of his, and then I read "The No-Cry Nap Solution," and it discussed this very issue. Apparently 45 minutes is a pretty standard sleep cycle, and although a lot of kids will sleep right through the end of a cycle, some will wake up like clockwork at about the 45-minute mark. The book goes into more detail, but basically the author suggests lurking next to where your son is sleeping right around the 45-minute mark, and the MOMENT he stirs even the slightest bit, do something to lull him back to sleep (pat his back, whisper "Shhhhhhh," gently rock the crib...whatever works for your child). If his waking is just due to the natural sleep cycle, he should fall back asleep for another 45 minutes. This has worked great with my son (though he's 16 months old, so obviously not eating as frequently, etc.), but I have to say, the author of the book said that after a week or so of this, the child would likely start sleeping through the 45-minute break on his own. Not my kid. It's been more than two months since we discovered this little pearl of wisdom, and I STILL have to lull him back to sleep after 45 minutes every day. It doesn't work every day, but it works probably six out of seven days of the week, so I'm happy with that. Good luck!