I think that's your body getting you used to it. I used to ignore people when they told me I wasn't gonna sleep anymore when I had the baby.... And it was so true. I could cry and cry in the morning when I couldn't resist my eyes open anymore and the baby still awake:. So he sleeps all day and I don't sleep more than 2-3 hours cuz he needs to eat and I have things to do. Wow... Fortunately it lasted like 2 months.. Things are now better. But take it like you're training for your nights with your newborn!! The most exhausting but beautiful experience ever