Your baby is stay awake in night. This is normal phenomenon. Let me explain why. When you were pregnant, your baby was inside a bag filled with water. During daytime you use to roam around in house leading to swinging kind of movement to that bag like swing, and baby use to sleep. During night time after you lay down those movement stopped and baby started activity. You must have noticed baby kicking in your tummy more in night times. So after baby is born, babys biological clock is still the same and it will take atlest couple of months more to normalise. so, dont worry. happy parenting.